Probably not. It might be a pain in the ass but realistically you’ll be able to work with banks/utilities/work to get access back. As long as you have access to your email as well you can likely recover your accounts. Files are likely the biggest risk, remember to keep regular backups and even this can be recovered.

It depends. If everything is stored unencrypted on the drive it’s pretty easy to reset passwords or boot to a USB and access everything. If it’s locked down hard you could be SOL. The worst I’ve seen happen is the loss of family photos with people who had passed away so they were irreplaceable.

I don’t think I’d use them for anything other than their intended purpose if you don’t know exactly what’s in them. For the leaky ones, you could probably collect the gel into some other sealed container like an old jar (not totally filled). Then it would still work well as a cold source for coolers/lunch packs.