My landlord pays the electric bill, so that part is not a worry for me.
Perhaps not, but someone pays in the end. It's a kind of theft, and I hope you think about remunerating your landlord.
I get around 20kh/s between 2 CPU's when mining FeatherCoin. I am mining on MultiPool currently.
If you're asking about Feathercoin mining you should ask on the alt coins board. If you're asking about bitcoin mining, then you'll need to use the lowest share submission difficulty a pool has.