For those who liked to know:
With a bit of a hint from Mmannai I configured the client to have a fix IP address, disabled windows firewall on both W7 64bit server and W7 32bit main HTPC client and also configured networking only for IPv4. Now remote control works fine.
Nice to know:
I've upgraded the server to 1.3.0 and IPimp works as it did in server 1.2 (client is still 1.2.0)
The procedure I posted for RicoHTPC to play music is one that works as a charm. A few days ago my little girl had a few friends visiting, and I've been playing DJ using my phone
2 things to tackle for the moment:
-Whenever I press the "now playing" button within IPimp my MePo on the client generates an error.
-I've tried what gtfreymann suggested to not have the annoying layer when streaming to my android phone. Did not work, unfortunately