staff

do i have to have a doctor and commercial manager to race.

I think that you do. 

Don't forget that the "auto-sign" feature will sign the lowest level, but cheapest, staff for you. 
This has for me signed doctors and commercial managers for 1000 per race.  I haven't been able to manually sign staff for less than 200000 per race yet.

Don't think you do, but I'd recommend as high a level doctor as possible, and then auto-sign a commercial manager.

Hi Ali,

You do not need to have a commerical manager to race. They essentially help you sell more merchandise when attending races. However if you have good income from sponsors and achieve you sponsor target (you get these every race i.e. Driver 1 finish 17th or higher) you will earn enough money. I would advise you spend the money elsewhere and assign you staff to design instead.

The docotr isn't crucial either,however i would advise you have him/her as it allows you to do driver heath training which does fall over time.

Hope this helps