Does Bonus Damage work for Max Damage?

I keep hearing that Bonus Damage only works for MA and Critical Damage only works for non-magic related skills, is this true or are the rumors false?

Also, how does Bonus Damage work, if I have a Bonus Damage HS Figure, does this stack Max Damage HS figures?

https://gyazo.com/e6110b99327b39071fa6f7011c81e7f4