For DLC I believe quarterly would be best.
As for what should be in the DLC I would like to see more quests and items but only lore friendly ones please.
What I do not want to see is more races unless they can be made to fit the lore of the Elemental universe.
What I really want from Elemental is the one thing that I don't get. What I want is a sense of the epic; from exploration and quests to nation building, the clash of armies, and diplomacy. However when I play the game I simply do not get that sense at all. When playing it I only get the sense of playing an interesting but unimmersive and un-epic game. I think it is a good game, however... it's just missing that quality that makes it feel epic.
So what is needed to make a more immersive, visceral, and epic game? First make cities feel like cities. While not taking up a large amount of space on the strategic map find a way to make them feel like real, living, breathing cities full of bustle, life, and centers of things. Cities are the centers of a civilizations culture, economy, industry, etc and they in some way should feel like it. How to get this effect in a limited space I am not sure but for the game to become epic I feel it is necessary. Also the land around a city, it's area of influence, should automatically change as land is cultivated, minerals are mined, villages with Palisades created, etc. What better way to see your civilization make an impact on the world then to have your territory change and develop over time. The player need not manage any of this it would simply be a graphical representation of the people of your nation spreading out from your cities and taming the surround world within you territory. To add even more depth and a more visceral feel two more things should be added to this. When monsters or enemy armies inter your territory they should leave a trail of devastation though the fields, villages, etc which will take several seasons to fix. This will make a more visual and thus visceral feel to people invading YOUR territory. Second the degree and quality of the improvements in a cities surrounding territory should be greatly influenced by your cities level.
Make armies feel like armies. Having armies represented by a few men immediately kills immersion and leaves a sense of... for lack of a better term... un-epicness. An idea for this might be to have armies in tactical battles take up multiple squares rather then just one. This would allow for two things. One more troops can be seen for each unit of men making a company of soldiers feel like an actual company of soldiers. This in itself would automatically increase immersion and make a battle feel like a real battle instead of a few people beating on each other. Second it would add more depth to tactical battles. There could be other ways to make armies feel like armies that would require less in the way of coding. If there is then by all means run with it. Just give me the sense that I have an army and when my army meets an enemy army I want it to feel like an actual clash of armies. To make the game more immersive, visceral, and epic armies need to feel, look, and act like armies.
Make quests more special. In terms of tactical combat two thing should be done. First most quest should only be fought out by heros not with armies. When your heros come to some ruins the army stays out side and the heros go in. Second tactical maps for quests should be special. If your party of heros wonders into a fortress the map should be of multiple floors with rooms on each floor with something of interest in each room. Whether it be a cave, a tomb, a ruin, a fortress, etc. it should be an actual, tern based, tactical dungeon to explore and conquer. Whether it be a monster(s), a person to talk to, loot, puzzle to solve, etc. it should have something in every section of the dungeon. This will set quest tactical maps apart from normal battle tactical maps and will make it feel like real dungeon delving. Overall this will make questing more immersive, fun, and epic.
Quests should highlight and give depth to the Elemental universe's lore. The stories they tell and the loot they contain should all flush out and promote the lore of the Elemental universe. This will increase the players immersion in the game and in a small way cause a greater investment in the game world. Also enough quests should be made, over time in DLCs of course, that one could play five different games without running into the same quests twice thus increasing immersion and interest in each game.
I could go on but I believe I have made my point. The game as is only feels like an ok game. I, for one, would really like this to change. I want Elemental to became an immersive, visceral, and epic game. Even if you choose not to incorporate the above suggestions into the game please look at the game and ask yourself, how can I make this game feel, look, and play more epically? How can I make cities feel like cities, armies feel like armies, quests become more immersive, lore give the world a foundation and meaning? Think big, think grand, think epic.