Hi Luthio, thanks for reaching out. The engine you're looking for is Renpy which is to my knowledge the greatest VN engine out there (support the project at renpy.org).
For assets, it's worth looking through the credits in the About section of our game. We use a lot of different assets and it's too much to list. (Abe actually doesn't have his own sprite, haha). For sprites I'd say Sutemo on itch has good free sprite packs that are good for setting up a game. Paid I'd say Sasaichi is one of the best.