Welcome to the forum! I believe 99% of the pumps, both battery and hand pump, come with 3-4 adapters to fit most openings. The weather dictates how much air you use. If it's warmer than 80, use less to allow for expansion, if under 80 use more. At least that is how I was taught. As for parts, maybe on Craigslist once in a while or you can try a sports classifieds page on Facebook. Be safe, have fun and remember, try to find someone to go with you if you aren't familiar with the pontoon or the water. They are a blast, but can be treacherous, too. A PFD and an anchor are essential, also.