Is there any chance we can get some extras like art, manuals and such? maybe some Behind the scenes?

It wasn't in the original so unlikely.

You'll be glad to hear though the version of RE2 they are using will most likely have character art, 3d models and other stuff.

Don't remember what the PC original port of 3 had.

The ohgee Nemesis port includ'd as extras some desktop mascots of Jill, a Zombie, and Nemesis. Maybe even a Cerberus too, I can't recall. That said, the '97 computer release of the first game surely did have a manual of some kind and it should be included, don't you think?