The JMP1 has valves in it, but it's not a pure valve preamp as far as I know. As to the amount of gain it depends on what style you play, but I play in a hard-rock band with a definite Metal edge, and I don't even use the OD2 channel. The OD1 gives me plenty enough gain to dial in some great sounds.
As to pedals I honestly couldn't say as I've never tried it.
Muttley