Creation of Wordpress gallery with app. 1,000 pictures

I need to create an image gallery on my self-hosted Wordpress blog. The images to be used are already uploaded to the Wordpress content folder and can be accessed from the Wordpress Medie library. Thus, they are not to be re-uploaded - they already have an image URL. There are approximately 1,000 pictures. Please be aware that the images feature men's underwear products and thus contains partial nudity. If this offends you in any way, do not apply for this project. I'd like for image gallery to be divided into four categories: Briefs, boxer briefs, thongs/jockstraps, and swimwear. You need to able to make this distinction when you create the four galleries. I would like for the images to display in a lighthouse-style gallery. I would like for you to outline for me the best way to complete this task.