Clutch replacement info needed, questions about flywheel and main seal.. Options

[914zim]

Hey fellas:

I'm well into my clutch replacement project. Unfortunately, I don't get as much time to work on it as I'd like, but some time is better than nothing, I guess.

I was searching through the archives regarding clutch cable replacement today and I read something that got me thinking...

My car has only 76K miles on it - total stock. Clutch was slipping, which is why I'm replacing it.
I did NOT get any machining done on the flywheel, because of the relatively low miles and it "looked" OK when I had it out (no scoring, etc.). I got the clutch kit from PP with the new pressure plate and disk.

Is machining the flywheel an absolute MUST when doing this repair? What would NOT getting it machined do/cause?
Also, I ordered the main seal with the kit as recommended, but didn't come across any mention of it in the procedure. How can I tell if I need to replace it? Where exactly is it located?

I suppose I shoudn't have started putting it back together before I asked these questions. Dammit.

Thanks for any help.

Andy...