How is this update looking to be save compatible?
It's save-compatible, at least in my testing. There's an outside chance that *some* combination of factors might make a save not load, but I'd be surprised.
Also: if you're running with mods, at least some mods will likely require updates to work with .1 (but, in theory, should be fine with existing saves once updated, if the updates are purely for .1 compatibility).
I guess the changes to map generation wont take effect unless its a new game?
Right, yeah.
Did we used to have or is it a possibility to have faction specific starts for the future? IE - Start with small ship or mini-fleet for hedgemony, tri-tach, pirate etc Inc max rep with that specific faction?
You might be of Nexerelin? This isn't something I'm too keen on adding; I'd rather choices like that be made in the game rather than before the game. (Though it does make sense for Nex; just not imo for vanilla.)
I guess the seeds still output the same sectors. Of course, cannot rely on abandoning colonies to remove Decivilized due to that getting fixed.
The seeds won't produce the same Sector, no - that stuff is pretty fragile, and changes to Sector generation pretty much guarantee seeds producing different results.