Given that you're "into tractors" I'll guess that you have at least SOME rudimentary mechanical knowledge.
If you go the pontoon route I suggest you avoid 2 stroke outboards, basically there is no longer any need to put up with their idiosyncrasies. 4-Stroke outboards have been around for 1/4 century now and are a mature technology - OK, there are 2-stroke die-hard traditionalists out there.
I've never had one, but it is my CASUAL observation that folk (around here at least) don't take as much care with covering and storing pontoon boats for the winter.
Typically the top is taken down, but the deck is left uncovered. According to what the underlying decking material is you COULD face rotted ply wood under soggy indoor/outdoor carpets. Maybe 8 sheets to redo a deck, don't ask how I know this - OK, I helped a friend redo his. QUite expensive, simple, but quite a bit of grunt work.
Warranty ? Fergettit (-:
The only time you want your boat fixed is when everyone else needs their's fixed - usually YESTERDAY ! Again, if you're "into tractors" the best thing you can do is learn to become self sufficient, starting with driveway tune-ups and oil changes. Set aside a little plastic tackle box and carry the tools on the boat that you use for maintenance. As you get into bigger repair projects, e.g. water pump replacement, make sure those tools also migrate to your on-board tool box.
DEFINITELY go used for a first boat, plan on keeping it for 2 years while you form better ideas of what you REALLY want for the longer term.
BTW, coast guard safety course is a good idea - I should probably take a refresher.