I rented a wetsuit for a race last spring - a bike/tri shop in my area rents them for $35 for the weekend. However, for big NC races they are all reserved months in advance, so you have to be on the ball!

My main rec is, by all means practice in it first! I was able to pick mine up on a Friday afternoon before the race and take it to the pool. Because I was in a hurry I only did a couple of laps in it, which really wasn't enough (this was the first time I'd worn a wetsuit). Come race day, I struggled mightily on the swim, and part of it was being psyched out by the unfamiliar feeling of the wetsuit, especially the tightness around my neck.

If you can practice at the race venue or in another open water area, even better!

I did not bother spraying myself all over with Pam on race day - I find that really gross, plus how much of it really remains after swimming a mile or more? I did grease up my ankles with bodyglide, in hopes that it might help in ripping off the wetsuit - no idea if it had any effect.