Regular anti-freeze will do just fine. If you want to get the 'good stuff' go for the LP coolant:
http://www.amazon.com/LP-COOLANT-STREET-GAL-RED/dp/B0029L7QX2I recommend AMSOIL scooter oil, 10w 40 fully synthetic. This varies from the manual a bit, but engines that I've worked on that are using the AMSOIL (or any other good synthetic really) seem to be in better all-around shape.
The Grand Vista 250 does not have a typical oil filter. It just has a metal mesh screen that is held in by a spring and the oil drain plug. That plug will be 17mm if I remember correctly. Spray the screen out with some brake cleaner after you drain the oil, and make sure it's dry before you re-install it.
Capped nipples on the tires? No, no lubricant is needed, but you might want to check that the proper tire pressure is in the tires. The proper tire pressure may be on a sticker on the bike somewhere, but I always go by what is written on the tire. Probably 36 PSI in your case.
The reading on the belt housing is for your gear oil. There is a drain bolt and a fill bolt to change the gear oil. I don't normally heed the measurement... just drain the oil out, put the plug in, and fill the gear oil up until it comes out the fill hole. Let it drip a few minutes so that the oil becomes level with the fill hole, wipe up the mess, put the plug back in and you're done!
Hope this helps!
~Josh
