Curls
Barbell, Preacher Curl, Spider Curl, Hammer Curl, Reverse Grip Curl, Cable Curl, Banded Curl(+ Barbell).
Mix it up. I like doing cable because you have a constant tension what you dont get with barbell or preacher. Spider fixes that issue with preacher but your gym needs to have the right kind of preacher bench.
You also want to do some movements that hit the brachialis and forearm, which are going to be neutral grip like hammer curls or even pronated. It also gets more attention when the bicep is shortened due to your shoulder/elbow position, think hanging from a pullup vs standing when contracting the bicep.
I usually do Spider/Preacher drop sets, then hammer, then cable on my higher rep day. On lower rep day I will just do free weight ez-bar sets alternating between inner and outer grip positions then finish with cable.
Abs 'freeweight' are bw/weighted decline situps, hanging leg raise, Dragon flags, planks, rollouts. Cable you can do pulldowns, wood choppers(obliques), palloff press, side bends...
For hanging legs you can get to the point where you keep your legs straight and you just draw a circle with your toes, start with a small spiral and work outwards. Recruits all sorts of things in your lower abs/upper legs.