THe reason the oil is coming out is due to you not using this trimmer on full throttle. They are very cheap and nasty (Though powerful!) units and need the trigger completely depressed when in use, otherwise oil starts to leak out. I understand why you wouldn't want to do that due to the horrendous noise these machines make at FT, but that is your reason right there.
As for not starting, try draining the tank and putting in a new mix of 2 stroke fuel. If that doesn't work, then gum deposits have probably made themselves at home in the carby or fuel line. Unless you know how to do this (like the above person suggested) then you will need to take it to a repair shop.
Next time you buy a trimmer, I highly recommend saving up a bit more money and going for an echo, or any other top notch brand, as ryobi ain't what it was ten years ago.
Greg
February 2008