The shops at Downtown Disney & dining ( exluding PI which opens around 3 or 3:30 ) start opening around 11:00. Guest Relations opens slightly earlier than that - but I do not have that time at the moment.
You can walk around all of DTD's "streets" for free. As mentioned, you only need tickets to go inside Cirque, DisneyQuest and the Pleasure Island clubs.

You can also walk the "streets" of pleasure island for free and buy drinks and such outside.