Did you mechanic friend tell you the bad news about timing belts and "interference" engines. Basically the motor is stuffed, you will need at a minimum to have the motor removed and stripped and some valves replaced. May need all valves replaced and some pistons too if you are unlucky.
for what it's worth, the timing belt was not a cause of any other issues (unless it was on wrong all along), so there must be at least 1 other problem as well.
From here, depending on how keen you are, it is either throw in a second hand motor, or rebuild the one you have. The first option is a little cheaper but more risky because you don't know how the motor is.