I would think so, since the Diplomat class claims it reduces the cost, though I don't know if the modifier would work for a faction trait rather than a sovereign trait.
Yeah it doesn't unfortunately (as far as I can tell).
How about being unable to interact with computer factions except for issuing declarations of war and negotiating peace
Yeah I tried to mod that in (blocking economic and trade treaties) but couldn't get it to work. I might have another look at it though because it would be the best options for Isolationist.
The consulate thing is a good idea thanks joeball/NM and yeah possibly some other improvements will go through them. Maybe reduced income from Merchants and similar improvements, that would make sense.
"Oppressive Bureaucracy" - something like reduced growth and research sounds about the right fit for what i'm after.
OK thats pretty good, some ideas there should get me out of the rut... thanks guys.