It has been a long time since I played Vampire, but - not only is it possible to do a group creation followed by individual preludes - it's the best way to do it.
You will probably need to have a gap in time between the creation session and the first Prelude. There will likely be some tailoring needed once you know the characters. But that's not a huge problem most of the time.
Character Creation for the Mechanics and the Meta
The Character Creation session should be used as a chance to have players become familiar with the system if they aren't already, and to discuss a few details of their characters to ensure they will work together and not have too much overlap.
You also have players discuss meta elements. Perhaps two players want to play rivals. They can discuss these details during this process, decide why they're going to be rivals.
Work up the full character, but I'd suggest telling players that no choices are final. Give them a chance to make changes once they better understand the mechanics and the setting.
During this part of the process, you needn't discuss more than the bare minimum of setting details. You know, just enough to make sure the characters will all fit within the premise. "You're all newly embraced kindred in the crazy world of high finance in the 1980s. Think American Psycho meets Vampire Diaries." Just enough to ensure the characters will work in your premise, and no more.
Prelude for the Setting and Story
Once you have the characters set, you can run individual preludes. This is the stage where you begin to introduce setting and story elements, and it can be run as free of mechanics as you and your players are comfortable with.
It need not be less interesting just because the characters are mortals. But making a story compelling does depend a lot on the GM. If you make the journey memorable, it will be awesome.
The last time I played Vampire, my GM did it this way. I built my Assamite, and then we roleplayed his journey from boy, to man, to trained assassin, right up to the scene where his mentor bites him on the neck and then hangs him up on a meathook. It was horrifying, and gut churning, but it was never dull. Along the way, my GM hinted at what it meant for the future.
You mentioned Initiations in Dogs in the Vineyard. As a GM, I've used this idea in preludes for other World of Darkness games (and other games) to help make them memorable. Players make characters, and then I ask them to ask a question we will answer during the prelude. This helps keep them engaged as they search for their answers.
This way will preserve nice balance between player agency and GM mystery. Players have freedom to create the characters they envision within the limits of the premise, but the GM doesn't reveal too many secrets too soon. I've played it, and run it, and it works well.
Both.
Ordinary vampires, when exposed to sunlight, take a number of levels of Aggravated damage each turn equal to their Bane Severity. (p.221)
Thin-blooded vampires, when exposed to sunlight, take one level of Superficial damage each turn. (p.113)
Thin-blooded vampires that have the Day-Drinker merit do not take any damage from sunlight. However, while exposed to sunlight, their health tracker has half the usual number of boxes and they may not use supernatural powers or disciplines. (p.183)
Best Answer
It's true: thin-bloods don't start with any points in any disciplines. You build a thin-blood character using the Merits and Flaws on p. 182-184, taking one, two, or three Duskborn flaws to balance the same number of Duskborn merits. You only get Thin-blood Alchemy if you buy the Merit to have it, and some Duskborn just won't. Same thing with permanent discipline dots.
If you have Thin-blood Alchemy, you have a number of recipes for effects. If those recipes are for unique effects, like Far Reach or Envelop, the duration will be listed at the end. If you've got recipes to simulate other powers, they last as long as those powers say they last; after that, you'll need a new brew.
Each of the three ways to brew corresponds to one of the Attribute categories and reflects a different style. Athanor Corporis is Physical, and it means drinking lots of different things and using yourself as a blender to mix them. It takes three turns to change powers, but you don't need anything but yourself. Calcinatio is Social, and it means turning humans you know into walking potions; each is set for one power, and you get it when you feed from them. Fixatio is Mental, and it's the one with all the bizarre ingredients and mad science props. Those brews, you prepare in advance; there's a limit on how many you can carry and store, but it's easy to have many and switch between them.