noob question - mecanim

So if I understand correctly when using Mecanim; in order to apply pre-made anims from the Asset Store, the imported .fbx has to adhere to Mecanim bone naming conventions, be in a t-pose and nothing more?

BUT if I'm not going to use imported (read: pre-made) animations, I can just import my own animations using any sort of bone names, etc?

Thx