Yes, I used a snap line and a dremel tool with 4 in blade. Be sure to wear eye protection or a face mask.
You might want to quadruple up on them if you don't want a bunch of holes punched thru by marble sized hail. Don't use wood or you may too have rot at almost every screw. You'll know when you find pulled out screws all around or when the wind rips the panels up.
Your spacing really depends on if you get snow in the winter and how much.. Where I live, I spaced the rafters every foot and used metal roof screws (the ones with the rubber gaskets) to screw it in. The plastic strips I think that you are referring to I used on the panels to stop wasps from making nests in those spaces. Don't forget to trim the sides with metal L to stop random wind gusts from getting under the edges and ripping that roof panel off. Also do a slight overlap on each panel (use clear silicon caulking to keep it more watertight)...
No these panels should not be installed at all. Unless you want to watch the screws pull out and panels rip off in the wind watch or marble sized hail just pass right thur. Be warned before you have the same terrible experience I've had.
8 foot to long how to cut
I believe they will work quite well.
I installed a screw in every 3rd valley, and on every rafter- so roughly 15.
Not at all. Eight years of mile-high Colorado sun and they're still clear as the day they were installed. Be sure to install the panels with the UV protected side out, as labeled on the panels.
Yes, there is a smoke grey color available and you can simply cut down this 26" wide panel to the size you need. I used Fiskars sissors to cut this stuff easily.
No, but I leaned on mine to reach my fastening points on my greenhouse roof ..