[p_r_i_m_e_r_a]

The answer to your question is yes!

Yes, IMO you can use your stock tranny. If this route is taken, you must baby your tranny(no slamming into 2nd)
Yes, you will need a new tranny after you break the first one.
(Chris's black 500WHP 200SX is on its 12th)
Yes, a 300HP car should have an upgraded suspension if it wants to stop.