Re: Garbage Matt points don't go where expected

I'm sorry that I can't answer your basic question regarding the garbage matte points because I don't work with them. But as for your timeline needing rendering, here's my suggestion:

Make sure that your Easy Setup is accurate for your video material.
Create a new sequence.
Drag one clip of your material onto the sequence. If the Easy Setup is correct (that determines the sequence settings), the clip should go onto the sequence without needing rendering. If the clip and sequence don't match, FCP will ask you if you want to have the sequence settings adjusted to match your clip. Answer "yes." Then your footage shouldn't need rendering in that sequence.

Remember that all projects open with one active sequence. If you change the settings on Easy Setup that will NOT change the settings on that first sequence. You have to delete that one. All succeeding sequences will have settings that match your Easy Setup.