Erm, I guess you don't desperately need any 3rd party apps to get you started. Just run through the available list and see which ones are useful to you right now tbh.
Stuff like Tyres, Essentials, Pedals, Track map and Delta should sort you out for now.
Car wise, just go with whatever you like the look of
![Smile :) :)](/styles/default/xenforo/vbSmilies/Normal/smile.gif)
It really depends where you're coming from and what your preferences are.
Settings
Have a good look at your button mapping options and
keyboard shortcuts.
I'd recommend at least mapping traction control to a button. You can do + & -, but if you're short on buttons, you can just use one to cycle through.
When doing your practice session settings, turn off STM and enable
factory ABS/TC. This means you can adjust TC/ABS on the fly if the car has those features - and there are usually different levels depending on the car.
Graphics
I don't know what your specs are, but you're probably able to max it out. It's not particularly demanding.
Just turn off FXAA and lower the reflection rendering frequency to medium/low or something. It's a performance hog and offers little perceivable benefit outside of photo mode.
That's pretty much it off the top of my head.
ED: And turn off suggested line. It really doesn't help, apart from giving you a rough idea. Problem is, it teaches you dodgy braking points.