I'm new to web development and therefore WordPress, which might explain why my questions to follow are written in such layman's terms. If you're kind enough to respond to my inquiry, please consider this when responding and write up your responses for the non-technical noob type such as myself.
To start, I'm wanting to build a site to serve a very specific purpose. I want to host images of textures that I've taken, thousands of them, have them organized categorically and allow users to easily browse these images and download them at various resolutions. I don't know exactly how I should monetize the site just yet, but there are already a few sites out there that do all this, http://www.cgtextures.com being the most popular and to start I will probably take a cue from them and try out a similar approach. Let unregistered users download a certain amount of data(image files) until hitting a certain download cap, upon which they will either have to wait 24hrs to make any more downloads or register and pay a small yearly membership fee to have unlimited access.
So my main question is what theme to start with? I've purchased my domain and installed WordPress and now I'm just browsing all these themes and it's a bit overwhelming. I'm mostly looking at photography portfolio themes, but these are mostly heavily designed to showcase the photos as art. The site I want to build is more about letting the user easily browse thousands of thumbnail photos categorically and download when they find what they're looking for. Again all really similar to http://www.cgtextures.com The only theme I've found so far that's even remotely similar is this one http://portfolium.wpshower.com/ from wpshower, but it doesn't seem terribly customizable. I imagine each one of these image thumbnails being a category, upon clicking one, you're taken to another similar page further breaking down that category into sub categories. For example: Cement Textures > Bare Cement, Cracked Cement, Painted Cement etc...
Also it would be nice if I could upload my image files at full resolution and have the theme or plugin create and organize separate files at different resolutions for me... Full, Medium, Small. I'm also toying around with the idea of letting my registered paid members have access to the camera raw file of each image.
-Host thousands of texture images categorically
-Easy to upload, manage, update thousands of photos
-Upload at maximum resolution and have theme/plugin create smaller versions to give users choice and help manage their download cap
-Free downloads for unregistered users up to a certain download cap in 24hr period
-Persistent GUI that shows user how much download quota they have left
-Registering for the site charges user a one-time yearly fee and grants unlimited downloads and access to camera raw downloads of images
So that's basically it. Can anyone recommend any themes/plugins as a good place to start? If any part of this doesn't make sense please let me know. Thank you in advance!