The polycarbonate is screwed to the frame using standard fittings from B&Q which include a rubber doughnut to seal it from water. Very cheap. The roof is 9′ x11′ and in total weighs about 20kg. Probably to much to hinge but easy to slide by hand without the complication of wheels & tracks etc.
I’m also keen not to lose to much garden, and my upright roof supports are removable. I have steel square section tubes set into the grass and the supports slot in when required and stored in the shed when not…easy.
Size wise I would say that 7′ square would be very tight. For the set up you describe I’d say 8×10 for comfort and 8×8 as absolute minimum.
Never had an issue with creepy crawlies. Maybe the daylight puts them off.