Would windows 7 be okay for some gaming on a pc? I have an used windows 7 and don't want to buy Windows 8 if I can help it.
Windows 7 is fine for gaming. Pretty much every game on the market right now is compatible with it.
Yes. Then upgrade it to Windows 10 to reap the benefits of DirectX 12.
I don't believe you can anymore. I thought you had to have Windows 7 prior to the release of Windows 10 to be eligible for the upgrade, even though you don't have to actually upgrade for around a year. I could be wrong, though.
You can purchase Windows 7 or 8.1 today and still upgrade to Windows 10. It doesn't really matter as long as you upgrade within a year from when Windows 10 was released.