Is the FS1 port for FO complete? Does it have all of the content? I want to start playing it there, just want to make sure that in the end some stuff is missing.

I believe the FS1 port for FSO is indeed complete with all content - just download the mod called FSport. Will you be playing on Windows, Linux, or Mac? (it doesn't really matter, it's just that some of the cutscenes in FSport don't work so well on the Mac with that encoding, but you can use the original encodings of the FS1 cutscenes and they'll work just fine.)

FreeSpace Port has more content than the original. It has the original and expansion campaign and a better version of the expansion called [url=http://www.hard-light.net/wiki/index.php/Silent_Threat:_Reborn]Silent Threat: Reborn[/url].

I think one mission of the original campaign is a little harder, because the missile homing is improved.