What's the quickest way to unlock a Sith, a Bounty Hunter and a small character in LEGO Star Wars: The Complete Saga?

There's a list of all the characters and how to unlock them on this page.

I've done what I can to find the "easiest" of each class, although they're a little poorly organized, so this might not be the most optimal path.

• The only story-unlock Sith is Darth Vader, who you can unlock after Ep. 6 level 5. Your other Sith options are pretty expensive unlocks.
• Wicket unlocks after Ep. 6 level 4. I believe he(?) counts as a small character.
• There are no bounty hunters unlocked from story missions as far as I can tell, but Bib Fortuna is available for purchase for 16,000 studs after Ep. 6 level 1.

From this, I'd probably clear Episode 6 first, and work towards 16k studs to get Bib Fortuna.