Hi,
Welcome back!
In an earlier thread, titled 5/3/1 Beginner Template Assistance Exercises; Jim Posted this:
Also, check this out from his blog: The 5/3/1 Philosophy for Beginners
I think this will answer your questions about the assistance work and Bench/Press work.
As far as progression, I believe you would progress as normal: 555, 333, 531 every time you hit a lift…
Good Luck and have fun!