Ron paid for the drinks before heading to the table which was, fortunately, still free. If his hands hadn't been full of drink, he might have tried to pull a chair out for Astoria. As it was, he waited to let her sit first. It was probably better that way, Merlin knew he'd have found a way to accidentally topple her to the floor or spill drink down her front with as awkward as he was feeling.
"Good enough to beat Evan about seven times out of ten." Granted, Ron had the advantage of superior age - but Evan was a Ravenclaw, and everyone expected them to be good at intellectual pursuits like chess. Ron usually came as something of a surprise - particularly as chess was one of the few times in his life he actually exhibited patience. "You play?"