If you want https access, I’d recommend caddy: it’s super simple to set up. If you have DNS set up for, say, home.example.com, this is the entire configuration to do a lets-encrypt-powered https reverse-proxy:
home.example.com
reverse_proxy 127.0.0.1:1787
I personally use Resilio Sync. More solutions are here: https://photostructure.com/faq/how-do-i-safely-store-files/#how-do-i-back-up-files-on-my-phone
I don’t have samba in the mix, as PhotoStructure, Resilio Sync, and Caddy all reside on the same box, but PhotoStructure will absolutely work with a library stored on a remote filesystem. Normally PhotoStructure will figure out that the filesystem is remotely mounted, but if it doesn’t, set the forceLocalDbReplica system setting to true.
Absolutely!
(Note that secure sharing is a feature that I will build soon, but until then, your reverse proxy can add auth).