Opinions Wanted - What clutch parts to buy and can I do it?

When you get your throw out bearing you'll need one with the collar on it or you'll need a press to re-use your old collar. They're available either way. Easiest way would be to just buy it with the collar already on it.
I don't remember for sure what size the clutch is on a slant but 9 1/4" sounds about right. If you're just putting in a standard type replacement clutch you should probably get the lever (probably either a Borg & Beck or a Long) type. A diaphragm clutch might require you to remove your over-center spring & that would just be more work.