Playing a game at the moment on 1.0X where I didn't bother researching trade, but used diplomacy and exchanged techs to get advanced trade. Thing is, the game wont let me build freighters until I have the original trade tech. This seems to work differently to weapons techs - if you trade for it, you can build it.
Also, and I suspect this might be fixed for 1.1, Two games now I have built ship assist modules on combat starbases which didn't do anything at all. I believe in each case I traded for the prerequisite techs rather than researching them myself. One game the modules suddenly started working after I started to lose badly, in my current game the ship assist modules still aren't conferring their bonuses to all of my fighters.
I suspect both problems are related to trading for these techs rather than researching them - when I research them myself they always seem to work fine.
Hambot