1) Use the site sponsors for everything. If you can find it somewhere online, odds are one of our sponsors can get it for you. Also a very important thing to remember, don't try to pinch pennies buying shit. It will end up costing you in the long run with these bikes.
2) Buy a Clymers Manual. I personally run Honda 85wt gear oil. Simply because they were smart enough to put the little spout on the top of the bottle.
3) You should be ashamed for considering a 4 stroke conversion. LOL. I know it's been done, but I'm not too sure on how successful it ended up being. If you just want to putt around, you bought the wrong bike. You won't burn up the motor, but as with any two stroke, you'll be changing plugs quite frequently if you're never hitting the powerband. On that note... the YFZ450's are coming down considerably in price. Might be able to find someone who would take it on a trade + cash.