Thank you for this useful information!
I'm a new Steem user since 20 days and a passionate hobby photographer. In the first days, it was really hard to find good photographers who share this hobby and to connect to each other. For me, the several photo contest helped me a lot to find such a community I want to connect with. Some of your mentions I didn't know before, so thank for sharing your favorites!
I think the biggest problem for us photographers it the misuse of the tags, filled with bad smartphone snapshots and many image plagiarism.
But we, the serious users, can help the Steemit community to clean up a little bit. There are services like @steemcleaners, @cheetah or @spaminator who fight against spam, plagiarism for the good of the community...
So... best regards and good captures... ;-)