I plan to host Conduit for my friends and family. Even if I invite absolutely everyone there would be no more than 50 users, max. But would it actually sustain and work, as it is not yet on 1.0 is a question. I do not want to host Synapse as I had bad time with it’s (lack of) garbage collecting. We do not plan to join very big rooms.
Most importantly, if you host it yourself, host is the usage (mostly disk) with how many users?
Conduit should run fine up to many hundreds of users on a single node as far as message passing goes. For the storage part, you’ll only operate as well as your storage solution. I’d honestly expect to invest some money on that part if you want the system as a whole to operate well, because some of the Matrix message handling is synchronous to media if attached to a message.
Depends a bit on how much images and videos get shared. If its mainly used for chat by a bunch of people and a few gifs and stickers in-between, it shouldn’t consume that much storage. But sure if you frequently share all your vacation photos, the cache is going to grow fast.