On the Rm2k's Steam version, you can fit up to 1000 pictures on the same screen.
Another database objects (Charsets, Chipsets, Actors, etc.) the limit is 9999 items, that's a huge value to a Rm2k game so don't worry about it
I've been working on something on and off for a few years now, and I've been reluctant to share any details on the project before I had anything playable because I did not want to generate hype only for the project to go back on hiatus. That being said I believe what I'm working on is very unique and pushes the boundaries of what RPG Maker projects can be. Bold claims, I know but just wait.