Wall thickness

Is 1/8" or 1/16" better to work with? What's the advantage of using one over the other?

1/8 is better because its can take a bend and won't kink. The only bad things about 1/8 i can find is that its a little bit more expensive and would put a little more force on ur waterblocks if they are bent like 180. my NB block, for example, had weak springs for mounting and with the tubing pushing it in one direction, it barly had any contact with the NB, that was resolved with a replacement spring. if u decide to go with 1/8" walls i'd make sure all ur blocks have good contact after installing.

Yeah, in a case, you won't be able to make any bends with the 1/16" wall tubing, unless you use the Cool Sleeves spiral plastic tubing wrap. Check it out w/search.