Can I wear shorts, a t-shirt, and flip-flops?

Yes, some are dressed up, lots a casual

Mixed crowd. We went fancy but there were a few in shorts, tshirts and ball caps.

Mixed crowd- some dressed to the nines while others were casual. Whatever you're comfortable in will work, but the place is nice so our group took the opportunity to do it up fancy.

I wouldn't, I don't think you would feel comfortable. Up to you!

Yes, it's real casual.

I don't think you need to comply with anything.

You can...you might look a little out of place but no one will say anything to you

It's a fairly fancy place, but I honestly don't know if they have a dress code. Everyone was dressed pretty nice.