Liquid - anti freeze, make sure you get stuff that can handle very cold temps and will not freeze. You can order neoprene and various seal string type things from 3M, check the website. Dielectric grease from most auto parts stores, make sure it is non-conductive.
Insulation is the most important part of a chiller system. You can not have any tubing or any part of the water blocks exposed to air or you will have condensation dripping all over your components. Don't skimp on the insulation unless you want to risk a lot of $$ in dead hardware.
Good luck.