Just my two cents...but can't help myself. I wouldn't waste my time on sleds longer than 40"s. this will give you more than enough room for a 36" taper and a thin block at the end to hold them in place while they run.
I know that there are still people out there that think they are doing something special by running full length tapers or veneers, but I couldn't imagine anyone who knew what they were doing going that route.
I have never heard of a bow failing due to a lamination splice.
Wood is more available in 33"-36" pieces and in many species you will never find it longer than that. Everything will ship cheaper when shorter too.
Show me a reason why a one piece lamination is better than a two and i'll prove to you your wrong.
I'm just learning how to do this though so I might have missed something.
I can't advise yey or ney on the baby drum. I have some Griz equipment that works outstanding and I have some that wasn't worth a boat anchor.
I would say stay away from grits smoother than 80 unless you plan on staining veneers and they should be run at 120..probably. 60 will do for laminations and riser blocks and pretty much anything else except glass.
Instead of buying accessories, group that money and purchase the best sander you can afford...or almost afford
you will be happier.
Remember though, I was just throwing my two cents in there so this is just free advice and worth what you paid for it.
good luck, BigJIm