Chloe, I suggest that you don't waste too much effort to find the best CD right now because you will level up very fast so will constantly need to upgrade. 4 stars is enough right now in my opinion. You do want a CD that have a positive trait in either Acceleration, Braking, Handling, Downforce (these four are also what is most imortant to develop during the season, before anything else) and negative in reliability or cooling. (I would say that to have the correct negative is more important than having a correct positive.
When you reach Elite you need to learn how and when to switch CD's during a season to optimize your development for the current and next season, but no need to worry about it too much yet. Shoot me a message when you reach elite and I will gladly explain further unless you already learnt it by then :)
Your money and tokens are at the moment better spent in upgrading your HQ buildings. There are different ideas about this, but since you are running in a 2 car team I would try to keep your manufacturing at max level (5 stars = same level as your manager level) as much as possible. If you run out of parts to repair your car with, low manufacturing plant is the reason.
After that I think Design, Tech, Simulator in that order. You can completely ignore hospitality center and youth academy for quite a while. When you reach somewhere around 13-14 your leveling will start to slow down and you will have been able to max the first 4 important buildings and you can then start with the last 2.
