This is not always the case, but the smaller the bait, the smaller the fish. Bigger bait bigger fish. My personal best was off a 2" black beetle spin while fishing for crappie so it's not always the case. The smaller jigs will most likely trigger more bites and give you more fish. Not so much quality fish, but fish.
Alot of people start off with bitsy bugs as they are cheap. The first time you try a bait people want something cheap
As for trailers I just match them to my jigs. Blue black jigs get blue rage craws. Any jig with green in it, gets green pumpkin rage craws. Brown the same. Those are the only colors I use.
I also like to use tubes on swim jigs. Makes for some killer skirt action. I love black Blue tube on a black blue jig.