Gossip is more of a bare-bones interface originally designed to prove out a particular type of protocol. I recommend using Amethyst on android, Damus on ios, and coracle.social and snort.social on desktop (browser).

Relays could theoretically end up being topic or region or language specific, but at this time they are for the most part general purpose. Some relays offer spam filtering, others offer specific services related to "the inbox model" (originally proposed by the guy that wrote gossip) which isn't something you should have to worry about when getting started.

Most of your mainstream clients (mentioned above) offer a button to upload a photo, but ultimately they end up sending them to places like nostr.build and copying the resultant url into your nostr profile metadata.