The cut stuff does make for a much better ending. If you haven't read through it all already, do so now.
Presumably, T3 (or another party member) is on board the Hawk and manages to stop it from falling into Malachor V.
Revan probably locked the navicomp, I think with T3's help, in order to prevent people from following him to wherever he went. And T3 shocked HK because HK was getting too nosy. Possibly he introduces something that prevents the droid from getting inquisitive again.
I think droid planet was a victim of the time constraint. It was, like, nearly done and then they had to cut it. Designer was vexed mightily, I hear.
I like to think Bao-Dur's dead, 'cause it's tragic and everything. Anyway, the Remote/G0T0 confrontation was cut because the HK Factory was cut too. HK has a dialogue where he hints at finding the factory making the HK-50 assassin droids as a subquest. Well, at one point he would interrogate a HK-50 droid and discover that it actually the mystery sub-level of the abandoned Telos military base. At the factory, he'd create or activate another line of HKs - HK-51s, I think - and use them to shut down the HK-50s. The relevance to the G0T0 thing is that HK would discover the two droids at a standoff and choose between them. He'd decide that he preferred the Remote to G0T0 and try to kill the 'fat one', but G0T0 would retaliate with some HK-51s - but they wouldn't be able to harm HK-47 due to self-preservation protocols, and would side with HK against G0T0. Alternatively, dialogue exists that suggests HK could side with G0T0 against Remote and hunt him down, promising to end his existence quickly or something.
Oh, and G0T0 was behind the HK-50 thing, I think.
Originally, Mira, Atton, Handmaiden/Disciple and Visas were supposed to go after Kreia (and fail miserably). The Trayus Academy map suggests that they would be imprisoned and that the Exile could rescue them, but at the expense of his personal power. There was also some awesomeness with Atton, Sion, Disciple, Handmaiden and Visas - real grizzly stuff.
And the ending is either you going off to find Revan, or chucking Kreia off a cliff and staying on Malachor V, which is even worse. Still, there were originally tearful goodbyes for Visas and Handmaiden, and even the possibility that the game would end with light banter...