Hi there Geoff, nice boat and I hope you enjoy it and it serves you well.
I have the 96 2100SR with the 5.7 2bbl so here is what I can offer (based on mine of course)
1) 5.7 2bbl for 1996 is 235hp (that is what the Merc. manual states anyway)
2) I get 54-55 mph on glass with 2 adults on mine. I am running a Solas 21p 3 blade though at around 4000 RPM. 19p or even 4 blade 18p will give better holeshot and higher RPM but not as much on top end (maybe 50 or so?)
3) I upgraded my stereo and speakers, replaced the Convertible top (made by Letas Top Shop) and bought a custom cover for it.
4) I think a 19p 3 blade would be a good start (18p 4 should be fine as well). This should give good holeshot for skiing yet still give good top end
5) Just as SP stated already, local canvas or upholstery shop would be a good start. Bayliner dealers can get some stuff still and a lot of the other stuff can be found with some searching (either aftermarket or oem)