RE: Need to know what to do to rebuild an older nitro car and engine...im a NOOB
There is too many questions in this thread to even begin to answer effectively. But, I'll take a shot at some of them.
If the engine has good compression, and turns over smoothly, I would not attempt a rebuild at this time. Get the car together and see how it works. To test the servo, simply plug it into a receiver and see if it works. It should not chatter, and should rotate smoothly. The shocks are probably good, but will most certainly need to be rebuilt. New oil and seals at the minimum.
If you have a local hobby shop, I would recomend taking it there for possible identification. That way, we may be able to help you further.
Also, chasis are generally either plastic or aluminum. neither of them rust. It might be a screw that has rusted, and stained the aluminum.
The screw on the engine head is a problem. You might be able to find a torx head bit that might fit into it, but in all likelyhood the screw is seized, at which point heat might be the only answer to free it up.
Good luck.