Can't build structures

Well, I have mixed feelings about this game.  Parts of it have me wanting to do that "one more turn", but that "one more turn" lots of times is very disappointing.

First of all, they seriously need to add some tooltips and a GOOD manual.  This is just unforgivable.  So much is left to figure out, and without at least being given a little direction that is impossible.  Case-in-point, elementium.  That's been a huge PITA.

Okay--structures.  Maybe I just missed it somewhere, but is there a limit on structures?  I research and research and get all kids of nifty new structures, have the resources, but can't build them.  Is there a limit on structures?  Where does it indicate this?  I guess it would make some sense since there are limitations on space in the real world (but then again, think of urban sprawl!), but what really chaps my hide are newer, better buildings.  WHY can't you upgrade existing buildings?  For instance... I have huts at the beginning of the games, and when I unlock houses.  Why won't it give me the option to pay to upgrade these?  I wouldn't mind demolishing some huts to build houses, but when I try it then says the city "won't be contiguous".  What the heck???  Do I have to tear down everything outside of the hut to build a house????  This is just crazy.  And when I do go to destroy a building, I wish it would pop up the name of the building as I mouse over it. 

All-in-all, this game has lots of potential, but they need to really put a lot of polish on it.  I still haven't figured out the use for shards... they seem useless.  I think they ought to have shards increase your mana regen (if you control 4 shards, you regen an extra 4 mana per turn, etc.). 

Anyway, any help on city building would be appreciated!