SW3 - Storyline ending, free play (spoilers!)

[Razz]

I finished SW3 for NESF and im wondering when is last moment where im able to play free without completing story missions.

After returning from precursor system there were a bit of free time before rescuing abducted Ternie. Is there any chance to play free after rescuing Ternie? (for example different choices by shipyards and so on)

Are other storylines so different from NESF so it is worth to load older save and play for other sides? If so, when are those moments of choices.

Thank for reply