My game history mirrors yours and I have backed both DU & Star Citizen. They're both very different games, but i try to make a point to back developers that try to push boundaries & do something different. DU specifically for their server tech & overall vision. JC is also a self confessed fanatic, which is the kind of person you want in charge!
Now, the questions...
I don't want to piss off NQ cause NDA, i will say that I played DU over the Winter holiday for at least 5 hours per day. I tried the latest build of Star Citizen yesterday, but I only lasted a couple of hours.
So far I've played completely solo, it's still way too early to have missed out on any chances to "make it". I'd imagine everything will be reset before launch.
It's alpha, there will be bugs. If you can't tolerate this, wait for beta for fewer bugs or release.
I think that depends on your personal situation. I personally went with the $60 pack cause i can't really justify spending $120+! The pledges also include DAC (dual access coupons) which are used to buy playtime after release. The $60 pledge has 3 so that's 3 months of post release playtime paid for in advance. This will be a subscription based game after release.
My understanding from the info released by NQ is that everyone will get an STU. This will enable everyone to create an area to safely store items so that you can leave the game and come back, maybe months, later. I see it a bit like the NPC station storage in Eve. The higher level packs just give you more space from the beginning. If I have this wrong, i am sure someone will correct me!
If you are still unsure, just wait for the NDA to drop, then there will be loads more information available. They haven't given a specific date for this, but Beta is currently scheduled for Summer 2020.
I hope this helps.