I’m the exact opposite of you in almost every way. Setlist - that shits all new to me. Cool it exists, but I like to be surprised.
Earplugs - definitely. I’m old and a drummer so have always protected my ears.
I almost exclusively buy tickets online, because I don’t like standing in line when I arrive, I want to go in and get settled in some dark corner or the pit depending on the opening acts. I mostly arrive late these days.
Agree on getting to the front along the sides. Merch - I always buy in person. It supports the bands, you interact with the bands many of the times (or girlfriends), and it adds to the experience. Plus you see the product first and know it’s real.