If i was to swap my interior to the g20 black leather int. What are the things that I would need to go and do so, Obviously I need the seats, but for the front do i Need the brackets or is it plug and play?

Well, the only part that is plug and play is the rear seat bottom...

The front seats would either need to be put on your seat rails... or you'd need to fab up a lower rail that would work...

B13, b14?

99 g20 into a 99 SE

I got a good price of 300 from some local guy that is parting out his car and i want'd to jump on it ** anything and everything goes

For the set of seats? That's a pretty decent price... :D