I wouldn't worry about Sky Multiroom. It is true that they can't use the internal wiring, but that doesn't have anything to do with Envi. Satellite signals are very sensitive to attenuation (degradation) of the signal. The connectors that are used to connect the coax cable Envi installed cause the signal to degrade substantially. That's why Sky refuse to use them. In fact, they run a separate cable from the dish for each point in the house. So, you can still have multiroom, it just means you need a second cable down the front of your house and into your bedroom.
As for the speaker system. Envi were never giving us a speaker system, they were just installing wires. Those wires can be used for any set of speakers regardless of the company providing them to you.
I've gotten a data of Feb 26th for the install of my line from eircom. I expect I'll be waiting for at least two weeks after the line is installed to get internet access :-(