Centre board line is port side on mine as well - and in manual. I think photo was flipped giving a mirror image?
You can stand on the pop top (hinged fibreglass) but do NOT step on the smoked plastic portion - it is not strong enough to handle the weight.
Welcome to the 260 - it’s a great boat. Dave is the expert on the boat, but there are lots of knowledgeable owners on the site!
Mast raising is not overly difficult, follow manual directions. Take your time and make sure everything is free and in position as you raise. I’m assuming you have the gin pole and mast crutch.
Another helpful site, set up by a former h260 owner and site member. That has a variety of helpful information
Another is the manufacturers resources.