I like the 7" versions, you can always trim them if they are too long. I think actual Zoom trick worms are all this length, the shorter ones are "finesse worms"
Trig weightless, weighted, shaky head, Crig, splitshot, dropshot.....numerous ways to use it. Seems kinda light for wacky.
Depending on how deep you are fishing it, 1/4 oz should be a good starting point for you. If you are gonna get into heavier weights, I would say use tungsten so the weight doesnt look giant on the head of the worm (Trick worms are relatively skinny)
And as always, colorwise you cant go wrong with "dark"
Wayne