I doubt there will be a refresh for the MacBook Air. The 13" MBP is already a great replacement.

You need to understand there are 2 ways to run Win on Macs: boot camp and virtual machines.

Boot Camp simply boots your mac to run windows. It'll behave just like any other windows laptop. Battery life is slightly less compared to running macOS simply because windows is not optimized for it. But this way you get maximum performance.

Virtual machines (by using software such as Parallels desktop, VM fusion, etc) is running windows on top of macOS. Obviously running 2 OS at the same time greatly decreases battery life and performance. For sure won't make it for 8 hrs. The advantage here is that it's a lot more convenient, and you can easily share/transfer files between both OS.

but a good point for you, the 2016 macbook/pros all can be powered using USB-C. So you can make use of a good powerbank and proper cable to power your macbook without worrying about power outlets (bear in mind, not all USB-C cables and powerbanks can deliver enough power)

no damage about running windows.

I dont know what software you need, but chances are you can find good macOS versions or alternatives for it.

AppleCare: you can buy anytime within the 1st year warranty period. Worth or not, hard to say...

i was an engineering student too. definitely boot camp is required, especially for autocad. some engrg softwares have macOS versions but normally they're not as good as the windows version.

very true. I was thinking OP could charge while walking to classes, lunch breaks etc. but yeah definitely bring along the charger (and extension!)