I started my CLS with decent speed set to get him above 240-245.
Now i was able to switch to a crit damage set and my speed is 235. If i was still using him in arena, i would keep farming crit damage mods to get back to 245 speed.
Crit damage set is harder to farm to the same total speed because you miss the speed set bonus of 10% base speed. You want him fast so he can debuff and give turn meter to the entire team. If you have thraen, you want thrawn (or leia for example) to be slightly faster so that they can remove evasion before cls turn.
Triangle, use crit damage.
Cross. Cls does not need potency because his passive gives 40% potency. Most people prefer offense and maybe protection if he isnt g12 yet.