Pretty sure it's illegal to require a minimum for credit card, but not sure on a fee just to use credit. I've seen places like antique stores and other online businesses charge more if using a card as opposed to ACH, etc.
On the carryouts, I'm not sure if it's tied to any new laws re: having to use recycled containers, etc, which was something I thought was put in place at one point, but those are much more expensive than regular styrofoam.
It's a weird spot. The price should include the takeout items, but there's a clear and growing difference in what it costs the restaurant. If you build the carryout price in, you certainly don't give a discount for dining in, although you can with specials and that's done (dine-in only). That's what the norm has been, one price regardless, but I definitely understand why it comes up and is attempted.