Can you please tell me if I launch a few actively working daemons bitcoin and point them to different -wallet, but the same -datadir will I have problems?
Yes, you will have problems. You cannot have multiple instances of Bitcoin Core (bitcoind) using the same datadir. That is not allowed and the software will prevent you from doing so. If you want to use multiwallet though bitcoind, wait for 0.15 to be released (it contains multiwallet support for RPCs, although experimentally) or compile it yourself.