1st question, no.
Every attribute can grow, except talent. Talent always remains the same, so you should buy the higher talented driver you can find (20 is the maximum).
2nd, yes and no. They all train at same pace, 1 train after each race. Of course if you race in a everyday league, your drivers can train everyday, but so can of the other managers...
In level 3 or 4, you can build the Gym, which allows you to train the Physical aspect of your drivers.
I recommend you read the guide 4 or 5 times, it is needed to learn some important things. Also enter in other league races and ask around... you'll learn a lot.
If you want a Strategy Tool for the races, try this one, i've made it... It's here (post #87):
http://igpmanager.com/play/?url=forum-thread_5/702