Unless you are with a strong alliance, you can expect to be farmed for resources in Ice (and Dark Marshes) on a daily basis. However, if you ship supplies out to High Kingdom regularly, it can be a good place to produce whatever you are needing, and of course you will need iron mines and works. Two is probably sufficient for a level 15 player, but as you grow you will need more. Having lots of farmhouses is useful if you plan to stock troops, but stocking troops will only make you a target if you are not well-defended in an alliance.
I keep 5 iron mines and a foundry at maximum level in full production (I am currently level 45), as high iron production becomes crucial for university research. Yes, you can farm for it, but farming in ice is miserable because of the graphics. Also, even though everyone there is minimum level 15, finding villains that are between the piddling level 4 and the daunting level 32 is difficult.