Ok, so if i write in 4 pool address, say: us, eu, ltcrabbit and one other; does my miner move on to the most active if one goes down, or does it split the work between the 4 so if one goes down, at worst ill lose only 25%?
Yes.
cgminer can be configured use different strategies: Failover, Round Robin, Rotate, Load Balance, or Balance. I use Failover, which directs all the work to the first pool unless it is down, then to the second. If the first and second are down, it switches to the third, etc. I think Failover is the default for CGMiner, but you can be sure by adding this to you conf file:
"failover-only" : true,