Can I include my 1099-B without upgrading to Premium? I got one this year for a small account that I've never touched. How do I include it with my Deluxe account?

I don't know if this will work but you can try it. If you just have one 1099B you can try to enter the proceeds on schedule d line 8a for long term  or line 1a for short term. If you have multiple 1099b forms then you would need to upgrade to premier.

Not if you are using TurboTax Online.  You need Premium to enter any investment sale.   If you are using the desktop software, you can use Deluxe to enter investment sales.