Um, I think the 2hp ones came with 14mm Bings, but you can look at the numbers on it and verify. It'll be like, 1/12/314 or something. You want the middle number. 12=12mm, 14=14mm, 15=15mm (it's highly unlikely you have a 15mm on there now). As far as I know, the stock intakes match the stock carbs, but you could always take it off and measure it if you aren't sure. Taking it off would also let you see the inkake port and know whether it's square or round.
If you're looking to upgrade your carb, probably either the 15mm Bing or 15mm Dellorto is a good choice. I personally like Bings, although there are plenty of people who like the Dellortos better. I'm pretty sure the 15mm intake Treats sells is for the Bing, but maybe he's got stuff I'm not aware of/remembering. Of course, you could save yourself a lot of money and just replace the throttle cable and gaskets on the carb you've got now -- 14mm certainly sufficient for what your needs appear to be.
As for what jets to buy, look at whatever you have in your carb right now. Buy the next three or four sizes up from that. So, if you have a 60, get 62, 64, 66, and maybe 68. I'd think that would give you enough options for now and for when it gets colder (upjet when it gets colder). Run plug chops to dial your jet size in.
Also, there's a lot of good info in the wiki ... you should check it out. (Performance Tuning category).