collecting rare fighters, maybe spoiler

[Nanaki]

In the FTU warehouses, Old Empire systems typically stock Wyverns, and New Empire systems typically stock Dragons

Is it possible i can pilot precurssor ships or alien ships?

Nope.

Anyone can share where else we can buy rare fighers, such as the other T series

There are only 3 T series ships, and all of them are only buyable in Charon.