Here is a link to the windshields. https://www.easternsurplus.net/PartDetails/2673/COM-3046-M35-M54-M809-Windshield-AssemblyIf those windshield panels are what I think they are, they may require some cutting around the gasket and maybe some redrilling of hardware holes in the frame. My dad went that route with his M37, which I believe uses the same windshield panels.
I'd consider getting them professionally fixed. I'm pretty sure @gringeltaube posted here somewhere what kind of channels are used on the windshield glass frames.
Regarding temperature, my A3 usually reads around 180 degrees when driving around. It'll get up to 200 or so on a hot day while idling or high-idling, at which point the cooling fan engages.
Looks like they have pre drilled holes.