hi,
il try to help you,
1/ my cluch drags. do an oil change with a decent make of transmision oil. sae 75w, 500ml if this doesnt help you might need a new cluch.
2/remove the rear mudguard and underneth there is two 10mm bolts. remove them and..................... air filter!
3/80:1 + 75:1 is fine
4/remove the tank and towards the top of the radiator is the cap.
hope this helps
have fun
max