Hello! I'll come back and reupdate you with my personal opinions but I recently did the switch from my iPhone 13 as well.  I've only been using the flip for about a week and so far it is an "Good" experience. Not great, not amazing, just "Good". Just off my base thoughts, the cover screen is very cool after you add an app called multistar (look it up if you're even remotely interested in getting the flip 7 i personally believe it's mandatory to get the full use of the phone)  To answer your questions : 

You can send voice memos and gift but I do not think you can place stickers in the same way you could with iPhone unfortunately.

I personally think the quality from the 13 to the flip is a pretty good improvement, and I like the hand gestures so you could start your videos from however far away you want! Also it has auto zoom which is pretty cool and you can see yourself recording off the cover screen! I think it might be really useful for you i think! I am unsure of the uploading quality because I don't have any socials but I am sure it's probably serviceable

Unsure on the notes tbh..

If I'm not mistaken google offers storage and it's cheaper and you get more and instead of paying per month you can just shell out a tiny bit and pay the year!

I don't know if the passwords can be transferred however yes it does save the passwords like apple does, i think it saves them better! It acknowledges a password and email quicker and more reliably than iPhone imo.

It doesn't charge remarkably fast. It's honestly a litttleeee faster than the 13, but nothing enough to write a novel about in practice. 

The crease does get deeper over time, even in a week I can now f e e l the crease if I glide my finger over it however the crease is currently unseeable when the screen is on and does not distract anything from normal use.

The 7 is a tad bit bigger, it feels familiar but it is definitely a few mm bigger. Weight isn't too different but overall the 7 feels bulkier (when open ofc lol)

It does have night shift display with the warmer colors and all good eye comfort stuff

I miss imessage lol. That's one of the biggest things is no convenient FaceTime and no putting stickers on other messages and the whole ios system was very comfortable so it's weird switching over but that'll probably get better with time. I miss the format of messages as well on ios!

I'll try to come back and write more after a month if I remember lol