About the facilities: the extra facilities will remain. However, if any are destroyed, you won't be able to replace them (unless you drop below your current max # of facilities, of coarse).
Null space skips all shields, including phased. The best counter is to not get hit!
But there is no (unmodded) component that will block Null space.
I've never used the resource converter.
Well, it's cheap, I guess. But it did cost you 1500 Racial Points that could have been put into things like, say attack or defence or construction rate etc. etc. etc.
Fighters and mines: I don't know off the top of my head.
Advanced storage is very useful. I'm rather fond of Crystalline myself. It's a good counter to all those Organic minded people out there. Propulsion experts is cool, too. Otherwise, I just crank up my attributes usually. See this
thread for a more detailed analysis of the Racial Techs.
Edit: grr. they changed the numbering on some of the topics.
[ 06 April 2002: Message edited by: dumbluck ]