Nope, that Rasa kit comes with everything you need, minus distilled water ($1/gallon) and some biocide or a killcoil...(togther, total of maybe $12) but either/or are fine alone.
PetrasTechShop link to PTNuke and Killcoils.
If you wanted different tubing or colors, you could certainly go the route of colored tubing.
You don't need premixes or anything like that...I'd avoid them. They won't cool better than plain water, and some of them, like FeserOne, have been known to gunk up waterblocks under moderate to heavy load temps over time.