1.  Equip/trade/shop

  They all are very similar in effect yet take up 2/3 separate buttons, surely one generic button would be better and allow space for the spell-casting button which  is on its own on the far right (i missed it for my first few games) to be with the turn based action buttons like trade/attack/explore.

2. End of turn summary when something is wrong.

  If a city isn't producing or research has stopped there should be some sort of warning maybe with a tick box to permanently ignore.  I know you get the zzz or a blank research icon but its easy to miss.

3.  "show tile yield on map"

  Should be default on for pioneers and a setting default (on/off) for the game

4.  In a tactical battle, if I pass/defend, I would expect say the greater of +5 defence or +30% defence.