Hi Ian,
No worries... not long winded at all... but what I suggest is to first write down or prioritize everything you want your site to accomplish and then start working on it bit by bit - like a checklist. Once, you get in your mind what the holistic goal is, think of the specifics that will get you there and then work on one problem at a time.
With this page for the users to upload photos, just so I understand... it sounds like you have not yet built the pages, correct? If that is the case, you could use the DataAssist wizard and use the wizard ability to filter results to determine who can see and update specific records. For example, when someone logs in and goes to their page with their photos and entries, you could have one application that filters by the user ID.
Again, I'm just talking generally here without knowing which exact thing you want to accomplish... so even if it takes a few posts or thread, just ask what you want... there are plenty of people here to help.
Best regards,
Brian