(Using stratum, 7 workers, i guess I should setup namecoind for ALL the workers ((every worker is a machine with 3 cards)), but I have yet to succeed in one's setup, that's why I ask for help...)
At Slush, NMC merge mining only supported on getwork, not stratum. So use getwork server if you want to merge mine.
Not true. Anyone who have NMC address get them but only getwork si contributing to NMC. So snice there is only 2% of the pool getwork you will get weary little NMC.
For the client look at Ufasoft Coin. It is for multiple coins and it is GUI not command line as NMC client. The only problem I have is that when it is downloading chain from internet uses HDD all the time so computer is weary slow.
EDIT: getwork is 10% fee so don't use it.