You could fashion an incline bench out of a flat bench by adding a couple of plates or something under the head of the bench. Will give you some angle at least. Also DO NOT arch your back as this effectively decreases the bench angle.
Thibs may correct me here, but I wouldn’t drop a pressing movement. I had my best results with the program with 3 (I tried 2). Also, YES do the days back-to-back. You’ll be fine, and will find that you are really ‘dialled in’ on the same, next day pressing workout. Stick with how it’s programmed. It’s an awesome setup.