Check out the TB-02 forum...lots of great info on there
I will try to sum up some of your questions here though. Towerhobbies is a great place to buy things for you TB-02. TA-04/TA-05/TB-02 suspension is all the same. Evo III parts all carry over(for the most part). The evo III diff halves would be good upgrades, but drifting is lower cost and does not involve buying all the hop-ups you can.