yes=) you can have a BS5 in the same system like your BS9000 and bv740 out no problem=)=) BS5 is the only music system you can have same with a other music system like your BS9000=)
Beosound 5 and BM5 are only a music system, and can not been use to record programs from TV. I dont think B&O will do that.
DVB-T/S is only mpeg 2 but DVB - hd modul is mpeg 2 and the new system mpeg4, the different is not that big, but when your cable/satelitt will go over to mpeg4 system you will not get the channel with the old mpeg2 system. But if you have satelitt you will use DVB-hd modul yet I think, is only for the cable and antenna on the roof.
With DVI you can only send picture, but whith hdmi you can send picture and sound in high quility. But is it the same picture quility.
I hope I help you a lot now and you can now buy a nice music system BS5 =)
Mvh Andybandy - MX 7000 - Earset A8 - (dream about a BV7-40 bluray tv)