General Support: Can I do this with Plogger?

Plogger already generates a pop-up menu with a list of the categories and albums you create, so that part of the job is done.

The defaults show a thumbnail on the main page for each category. So, if you restrict yourself to one category, that part of the job is done too.

The defaults for album pages are to show a page of small thumbnails for all the photos in the album (you can designate how many thumbnails per page.) The thumbnails have checkboxes next to them; the user can check as many photos as s/he wants, then click a button, and the corresponding full-size images will be combined into one large zip file for downloading. (You also can disable this feature if you don't want people to download your files.)

The pages for medium-sized individual pictures don't have a button for downloading files, but you probably could add one pretty easily if you understand PHP coding. In fact, just about everything is customizable if you can do PHP. The look of your gallery is determined by a set of templates, so an easy way to change things is to duplicate one of the existing templates and then start editing it. Even though I don't know a lot of PHP, I was pleasantly surprised with how many things I was able to do to customize my gallery.