A fan over the memory should be plenty for you.
The best pumps reliability wise are by Eheim. Not sure how quiet they are, but they are
very reliable. If sound is a major concern then you may want to us one of the PA120.x since they perform very well with low power (read quiet) fans.
Hmm, with GPU blocks I have no experience.(will leave this to the more informed)
CPU blocks I don't have enough experience either.(again will leave for the more informed)
If you don't want to mess with it
at all then you will likely want a res.
If only to avoid refilling it.
T-lines will perform a little better, are cheaper, and are much smaller, though. To each his own.
Edit: If you have the room and settle on componets that support it then I would go for the 1/2'' rather than the 3/8''