Chonosmoon

I would do them but I'm currently not available for commissions till May. You could always sign up to procustomizers there are plenty of customizers there.

I would do my research on each individual figure and see how much each one sells compared to a group.
if the prices vary for individuals and there is one that will not sell well alone you may consider selling as a team too.

Use acrylics

For Action figure joints, can't help you there, I only customize transformers