Career mode lasts 7 years, until and including May 2015.
Training
Max out Cardio to gain better training stamina
Max out Strength (decreases Cardio and Speed)
Max out Cardio/Speed (decreases Strength slightly)
Cred
The cred bonus of the logos add up, even if all the logos are alike. So just pick the one with the highest cred bonus, and place 10 of that one on your trunks.