Hi, I'm quite new to this (only have watched videos and read forums) so I might use incorrect terms and explain things unclearly, please ask if you need more information to assist me.

Alright, so I got a dell optiplex 7060 micro with an i7 8700, 16gb dual channel ram (sodimm), a 256gb m.2 sata ssd and 130w dell ac adapter. Some other currently not in use hardware that may be of help is a 1tb 2.5 inch hdd that was in an old laptop from 2017 (still works perfectly fine, did do writing quite a bit in the past but never even store past 200gb) and a 1tb 3.5 inch hdd in some sort of bay for storing film in the 2010s (haven't used for a long time but a few months ago I connected to it, could read and copy files from there).

My use case would be nextcloud for me, a friend in another country and 1 or 2 family member to backup data, we all have a copy on our machine and cloud backup. Next would be jellyfin and vaultwarden for my personal use, probably to stream some music that I listen to less frequently and movies that I torrent to watch a few times a month. I would also do research on running home assistant (now using a google nest mini and broadlink universal ir remote with the google home app and broadlink's app, looking to degoogle and rely less on cloud stuff) and a matrix server for me and 2 more friends. However, the emphasis is still on the 3 initial purposes.

I'm planning to buy 1 nas drive from 2-4tb, a ups for proper shutdown/notification in power outage situations and will buy an external drive in the future or use the old drives for backup (maybe once a week) if possible.

Now, to the questions:

1. Is the 1 drive setup actually suitable for my use case?
2. Should I use proxmox? Or do you suggest smth else?
3. What should I do to connect the drive? Use the sata connector of the dell optiplex micro (designed for 2.5 drives) and wire it to the outside, will it even provide enough power for a 3.5 hdd? Or buying a m.2 e key to 2 sata ports is a better option, and how can I power the single drive without purchasing a desktop psu?
4. What is the best choice for connecting remotely without consuming too much battery on the devices? I've read about tailscale, wireguard, cloudfare, and things like using my own domain.
5. I'm looking for old nas drives too because my budget is tight, what conditions should I aim for if I want it to work for another 4-6 years?

Any other ideas/suggestions for my project would be of so much help! Thank you so much!