I'm sorry Alkonium, but I didn't like any of those ideas. T3 being made into R2? No, they are two different droids. T3 is what was called a Utility Droid, and had a different body than R2. R2 is a Astromech Droid, and has a much different body than that. It is kind of a intriguing idea, but it is a little bit farfetched.
Second Star Forge? You have to be kiddding me.
Let me guess, we are going to have the same old party members to, and we are going to have to go to the same planets to find the *gasps* second star maps, that lead to another Star Forge! No way, lets not replay the first game.
Pretty much what Doc said about the Mustafar thing. Might be ok, but a little weak and farfetched. The HK thing might work, but personally I don't like the whole Galaxies HK thing on Mustafar. But it would be nice to maybe kind of hint at that.