congrats for deciding on the WC... i can only dream of spending 500bucks for wc gear.. lol but i m considering it VERY VERY hard to wc my comp... anyway, i'll try to help the best i can
go to dazmode.com and get the wc gear there.... daz is very helpful and located in canada!!
for tubing, i guess 1/2" Inner Diameter (ID) tubing is good, the Outer Diameter (OD) of 1/2" ID is usually 3/4" OD
I would get compressions (probably < 100bucks extra) instead of barbs + zipties.. i mean may as well right?
get right angle or 45degrees connectors also... since you are doing dual loops and there might be lots of tubing going everywhere... lol
are you going to OC the ram??? which cpu are you using? if the socket 1156, i m pretty sure their ram runs at 1.6v for the higher spec ones? ddr2 run @ 2.1V for my gskill ddr2-1000... so i m guessing, u dont need to wc the ram.
edit: didnt see you using p6t... so anybody out there using i7 s1366? not sure about the ram specs for that socket
why dont you wc the mosfets instead?