First off, welcome to the board.
Now, let's take one question at a time...
Answer to Question one; I'm assuming you know all the proper steps; priming, attaching glow starter, popping over the engine, etc. Usually, the standard settings that we all use are set all needles to "flush". These tend to be on the rich side, but since the fuel contains the lubricant the engine needs to survive, richer is better.
The idle air opening can be anywhere from .3 to .6mm. This adjustment is checked by removing the air filter and checking the opening of the carburetor. Remember to reinstall your air filter once it is set, fastening it with a cable tie. A good starting place for most engines is about .5mm.
Assuming your fuel lines are not leaking (you would see this manifested by several "dirty wet spots" along the fuel tubing), the next thing to check is the actual compression of the engine. Since it pops over and tries to run, I would assume that the compression is at least fine enough to get it to fire and run.
Now that the basics have been gone over, it's time to give it a test. I'm assuming you're using the correct fuel (nitro-methanol car fuel, anywhere from 5-30%). Using anything other than fuel intended for glow-powered cars can be fatal to your engine.
Next, fill up your fuel tank, and try to start the car. If it starts, it might die right away. This is normal, don't be discouraged. Turn the high needle down 1/16th of a turn (it does not take much), and try again. Keep repeating this until you get the engine to start and stay running for at least 10 seconds, then richen it back up 1/4th of a turn. This ensures you are richer than need-be.
Now, once you get it started and running, place it on the ground, and try to get it to stay running. The goal here is to keep it running. We're going to begin leaning the engine down now. First, we'll work on the high end needle (the one where the fuel line attaches to). Lean it down in 1/16th of a turn increments, until the engine has good top end. Every 1/4th turn, stop and check the low end needle. You should not have to go more than about a half turn or so.
The low end needle is checked/adjusted by letting the car idle until the count of 5. Roughly about 5 seconds, then clamp the throttle to 100%. The car should hesitate slightly, then accelerate. If it hesitates for about 1-2 seconds, your low end needle is perfect. If it bogs heavily when you accelerate, you're too rich, and the needle will needle leaning down, about 1/16th of a turn. Again, it does not take much. If it revvs high (or sounds like it's a single solid note), you're way too lean; richen 1/4th turn. Your ideal idle tone should sound like popcorn popping.
I am not sure if your car has two speeds on it or not (look at the front of the engine, you'll see a small gear, mated to a larger gear. If you see two sets there, you have a two speed transmission). If you have a two speed, the goal is to get the transmission to shift at about the 2/3rds throttle range. This is the ballpark for your tuning, assuming the shift point is correct.
The goal here is to have the car running with decent top end and fairly decent acceleration. Now, keep in mind, while you have the car adjusted... The needle positions will change from day to day. This is due to atmospheric conditions. Usually a 1/16th of a turn on the high end needle is enough to correct it. I always richen mine 1/4th of a turn before storing it, then re-tune it when I start to run it.
Remember to check your temperature periodically. This is done by using a temp gun, and taking a reading near the glow plug, or on the side of the engine under the cooling head. The temperature should ideally be around 235F (not sure what that is in C, sorry). You can get a cheap one for about $20USD that will serve you nicely for many a year to come.
Now, as for Question two; It really is a good thing you're not driving it now, as steering that is malfunctioning in any way is not safe. There are a couple things to check, but the first, and most obvious is the controller. Check the steering wheel to make sure the wheel itself springs back to center. It should return to center under it's own power easily (you do not need to turn on the radio for this, as it's all spring-based).
Hope that all helps!
