After borrowing a friends snowboard, now what?

honestly, I suggest you leave your borrowed board at home. If you're renting boots anyway, why have the hle? Renting the complete set- up will ensure that you get sized properly and that boots / bindings are compatible....no extra wiggles or mis-alignments. The rental will be good enough for first time and will be such that if you run over something or worse, you wont ruin your friends board. Rental shop work does herd people through, but that's what they do... got it to a science so they move em through as quickly as possible.... My other suggestion is to rent the boots for the borrowed board off- mountain in advance so you can by-p the mad house all together and have time to play around with them to make sure everything is in good order.