Which Operatting System would be better suited for my needs?

Lots of people have complained about Windows 8 being terrible, but I've been using it for a long time, and once we get past the start menu difference, Windows 8.1 is really nice.

Advantages of Windows 8.1:-

1> Faster boot times.
2> Lighter on resources. Believe it or not, Windows 8.1 is actually lighter on resources than Windows 7.
3> Tablet-style metro apps.
4> Option to use PC refresh and PC restore, they are like the "Factory reset" option on smartphones. If something goes wrong, you won't need to reinstall from scratch, you'll select the option to "Reset" and it will reset automatically as if it was a new install.
5>Can use System image recover right from within Windows, in Windows 7, to use a system image recovery, you'll need to boot using the Windows 7 DVD.
6>Lower power consumption, hence better battery life.
7>Airplane mode.
8>Hybrid sleep.
9>A better task manager.
10>Can mount iso images directly as virtual CD/DVD drives, without needing special software like Alcohol.


Advantages of Windows 7:-

1>Tried and tested. It's been around for a while, and everyone loves it.
2>Although more demanding on resources, it's still a light year better than Vista.
3>AERO. Some people complain about Aero being too distracting, but I personally love it. Windows 8/8.1 doesn't have Aero, and hence the Windows 7 desktop looks better.
4>Desktop gadgets. Windows 7 let's you install desktop gadgets that show live feeds from the internet, a clock, a CPU meter, a network meter etc, it's like that Windows Vista "Sidebar". Windows 8 won't let you install gadgets, and the replacement, "live tiles" cannot be placed on the desktop. You can sure have a live tile that shows you weather, but since you are not allowed to place it on the desktop, you will have to click on start every time you want to take a look at it.
5>An arguably better start menu. Although i don't find the start screen on Windows 8 to be very annoying, some people think it's one of the worst inventions and replace the start menu with third party apps. If you find the start screen annoying, stick with Windows 7.
6>"Previous versions" option is gone in Windows 8. And it's replacement, "file history", isn't a proper replacement at all. It only saves histories of files in your profile folder. Say you have a separate partition where you save your personal files, or say you want to take a look at the previous state of a file stored in a location other than your profile folder (Example C:\program files), file history doesn't work.
7>3D flip. You can press the Windows key and the Tab key together to see a 3D preview of all the windows you have running in Windows 7, and you can also switch between them. This isn't available in Windows 8, and you have the classic Alt Tab for windows switching, like in Windows XP, as the only option.

As you can see, arguments can be made for each OS. Select the one you like most considering the facts posted above.
The things you mentioned you'd be doing, can be done on both of them.
And not getting a physical DVD from the college isn't a big deal, you can always burn the downloaded image to your own DVD, or even make a bootable USB flash drive with it. A product key is all that matters, and no matter what you choose, your college will give you the install key
If you're using Microsoft Visual Studio to develop in C++, you'll need a very new version, the older version that I use myself, worked perfectly in Windows 7 but throws up a "Compatibility Issue" warning in Windows 8.1. Although I have not upgraded, I used the compatibility mode for Windows 7, and selected the option to "Run as administrator", and it works, haven't had any problems so far.
I don't design games, but other engineering stuff like AutoCAD, MathCAD, Visual C++, .NET, etc work fine in Windows 8.1