1. 3.75" line for the world-building, accessory-interacting aspect. With 3.75" you get horses (beasts for SW), vehicles, playsets, etc., that would be too big/costly for 6" scale.
2. Both were too much. 3.75" should have been $9.99, 6" no more than $19.99.
3. Both scales are good in that they meet different collector's needs. I would have preferred a modern 3.75" (like 2008) on retro cards, but that's just me. They may have saved money due to using the same digital files for both scales. 6" should have easily had 50 figures. 3.75" retro should have done all the 1982 figures, plus at least 5 from each of the other movies. Both were inadequate releases.
4. The PFP for 6" was okay, but those that open figures couldn't get a look at paint applications before purchasing. My only beef with the 6" packaging was the Brody/Belloq 2-pack, which gives you a box that can't be displayed behind the figure because you can only show one side at a time. So it makes display/storage a little more difficult.
5. The blisters on the retro line were okay. Most modern figures use blisters that are too big to display all the pieces. You can pack a lot into a small space. Just look at the 2011 SW Vintage Collection Emperor's Royal Guard. They say they want to limit plastic use, then do that.