Real lead times on a turnkey probably run about 3-4 months unless Tommy has caught up from where he was when I got my machine. Manual machines go out quick from what I've read. CNC kits could be a month or you could wait a year, kits have been the least predictable delivery-wise.
You do not have to pay up front. I gave Tommy a $1000 deposit on my machine, but not because he made me.
I have the NT spindle. Make sure you need it before you order it because you will definitely spend more money on your tooling if you go that route.
MD001 mill is an IH clone, quality will depend on how well they QC their machines. I think I remember hearing positive things about them, but I don't trust my memory completely.
I'm sure a BP will be quieter since its belt drive, but whether it can make a heavier cut depends on if you are able to find a machine in good condition. Although I'm a big believer in my IH machine, its hard for me to believe a BP in good shape couldn't slightly out-cut it in terms of metal removal rates. That being said I have used a carbide roughing / finishing endmill in my machine to make .025" cuts .815" deep at 35ipm. That's moving along pretty quick. I ordered a more aggressive end mill and a holder with a set screw and I expect to hit 50ipm or better.
My 2 pennies.