1 - Rework economy. This game needs effective means to drain resources from high lv players who already upgraded everything, because currently resource price in GCs is constantly dropping and for newbies its difficult to event get enough gold for lv2 lv3 upgrades. Maybe you should consider introducing temporarily buildings in adventures or maybe cost/search time/resource quantity of some mines (especially gold) should also be reconsidered.
2 - Hmm... like some ppl already mentioned research would be nice addition.
3 - interactive building list would be nice.

