Thanks very much for the information. Just one thing, you said 

" Even then, you'll still need to set the AI personality to 8 or 11 (Terran and Generic if you're customising races in-game)"

what does that mean and where do I change it, or where is there more information on the subject?

Manually editing the raceconfig means that you don't inadvertantly change their dialogue tags, which is how they pick particular lines to communicate with.  I don't know if it's just me but after switching personality in-game, it seems that dialogue tags are switched to those corresponding to that personality, rather than preferring the racial ones.

Go for a good number of opponents in a tiny / small galaxy, that usually creates quite some action. If you then throw in the Drengin and/or Korath, you might face a challenge.

On the other hand when it comes to larger galaxies it's often the Torians that dominate because they outgrow and outcolonize everyone else.

Choosing the right difficulty setting also helps; if you feel you're rolling over the AI, increase the difficulty. Especially at lower levels the AI algorithms have been dumbed down.

You don't need to edit the main raceconfig file.  When you customise your opponents an individual raceconfig.xml file appears in your saved game folder (this may vary depending on your OS) that you can edit with Notepad or similar.  So, no merging needed.

For testing the mod I usually play on Tough, with tech trading off (it benefits me far more than it does the AI) on a Huge galaxy.  I also have Tech Speed set to Very Slow, because it draws the game out a bit, but you may find it a bit too slow.  I would suggest you play with habitable worlds cranked up high if your computer can take it, since this also draws the game out and balances the AIs out against each other and you fairly well.  Scattered star clusters rather than Loose or Tight also makes things fairer.

The reason why the mods exist is because the tech trees are a little buggy in vanilla TA.  As a result, if you pursued weapons tech other than missiles, the AI would never develop weapons of their own.  Playing Metaverse became more of a chore than anything else, because so far as I know there aren't any races whose tech trees aren't a little borked.

Put your Mods here

C:\Program Files\Stardock Games\GalCiv2\Mods

When our Enemies win a battle, they called it a VICTORY, 

but when Empress Saint Mina, Our Living Saint wins a battle, they called it a MASSACRE! 

No MERCY!  No RESPITE!  

We are looking for players to join to become aggressive Admirals to lead your fleets across the Galaxy!

Empress Saint Mina of Ophelia VII of Order of the Bloody Rose of Orders Militant of Adepta Sororitas

I know there have been some "walkthrough" examples of games posted here in the past but they're hard to find back due to the search engine and the sheer size of the forum.

I would recommend that you post specific questions, e.g. do you have trouble in the early or late game, colonization, military, economy, etc. as it's easier to provide recommendations rather than describing a total approach to the game (which varies a lot by player anyway)

2. While trade usually doesn't rake in huge amounts compared to taxes, it does help. As you already know, far trade routes yield more (with the trade ships bringing in more cash when they are further away on their route); sending them to capitals of other races also helps though I don't know the exact relationship between trade income and the planet's economy. 10 trade ships can easily bring in 500 bc each turn without using any economic starbases
The most important impact of trade ships however is that they improve your relations with the races you establish trade routes with.

3. I typically start with 1-2 factories or similar buildings to speed up construction on a planet. I then specialize my planets, mostly based on any bonus tiles. Many of my planets also end up with only economic buildings and those 1-2 factories in case I need to upgrade my buildings. When I'm not upgrading, I switch their focus to research so those factories contribute a little to research.
Advantages of specialization:
- bigger impact of buildings that give X% bonus on a particular planet (e.g. forge, research coordination center)
- more concentrated output which allows to build unique buildings / wonders faster
- more concentrated output which allows to build large ships faster. I prefer to be able to construct a few large ships in a limited number of turns, rather than having 20 planets in parallel taking a year to build a ship each

4. This is common, depending on your settings (galaxy size, number of planets, number of habitable planets, number of extreme planets). Colonization is all about speed, both producing colony ships fast and researching/adding better engines so they reach their destination faster.
Researching extreme planet colonization technologies only comes in handy once the normal planets have all been colonized and you see a few high quality planets in your area.

5. At the start, I develop my home world to get some early ship production and research going, then I research trade to build an economic capital. My second and sometimes third planet are dedicated to ship production, my next planet to research. Beyond that I colonize but don't build on planets yet until my economy becomes stable or the planet becomes self sufficient (i.e. the additional maintenance cost of an economic building is offset by the additional income it generates). Once my economy is in decent shape, I'll develop some more planets into production / research havens.

6. Don't remember from the top of my head but I believe that's something you can change in the general game options / settings. I know that by default I see the summary view of hitpoints, damage dealt, damage received, etc. at the end of each battle so it must depend on user settings.

7. That depends on personal preference. For small galaxies I tend to go with 2 majors and random minors; for medium and above I go with 3-4 majors and 9 minors. While minors take up a valuable planet, they're great to trade technologies with early on and if you're the one to capture their planet you can end up with multiple economic / research / manufacturing capitals (especially after you've traded the necessary technologies with them, that usually causes them to start building those capitals).
I prefer to have a slightly crowded galaxy since it becomes more active, more close borders and overlapping influence areas mean more chances of wars breaking out.

8. I don't use them enough; military starbases can also be important to boost your military rating so you seem stronger. Some people make heavy use of economic starbases to boost their planet and trade income (but then put enough defenses and weapons on those starbases to make them less vulnerable).
I also use influence starbases in the same way as you do, quite often you don't have much choice if you want to avoid your planets flipping or if you want to pursue an influence victory.

9. Here again I'm not an expert; I let my original miner do its job but I don't know the benefits either. Some people prefer to convert it into a colony ship to speed up their early colonization though.

Try them both separately and see.

I'm not going to say that I have addressed the faults in all the races, but I have spent a bit of time on each of the racial tech trees that I have worked on, balancing them against the other races I have worked on.  I've also looked at various ship components and starbase modules, adding new ones where needed.

As a result, the AI tends to do things that an average skill human player would do, like ignoring defences for fighters and adding HP modules instead.  The way the tech tree is designed now means that human and AI alike benefit more from exploring the lower branches of the tree than by just charging straight up the main trunk, although progressing up the tree is still key to succeeding.  So there's less time wasted on time-intensive research like extreme colonisation when weapons and ships research is needed.

However, so far as really addressing the faults in the AI, that's up to Stardock.  If it were me, I would add some behaviour modification into the tech tree, allowing certain techs to weigh more when at war, when the economy is on the verge of collapse, and when approval is low, and so on.  Same deal with planetary improvements and ship components.  Having these things in the XML (rather than the one AI value that we have at present) is a good way of changing the way the AI behaves without needing to recompile the game executable.  As such it's of benefit not just to modders but to Stardock as well in improving the game.