Karassik as a basic practical book? I don't think so -- it's not for a beginner. Far better is to simply pit a couple competing factory reps against each other, and you'll get enough information from them to understand what's important and what's not.
Looks like others have covered just about everything, so I'll just add a couple items:
I prefer peristaltic over diaphragm pumps. Hydrogen off-gassing doesn't stall them, and it's easier to replace tubing than diaphragms. For small peristatic pumps, look at Watson-Marlow/Bredel. The...
