Just a guess, but I believe you will see the outer edges of the stadium be iron gates, which will open at the end of the game to allow for easy egress for attendees. Retail as part of the building itself will probably be limited to under stand concessions, and maybe a team shop, probably around the corner of Mint and MLK. Planning views for the surrounding sites call for mixed use residental over retail, low rise, maybe 4 - 6 stories. Think of the land between Poplar - Mint, 3rd - 4th. Also the south east corner of MLK and Graham, and across the street from the stadium on Graham. Between 4th and Trade on Graham will be the Amtak Station complex which has retail, and the land surrounding the Presto Grill has plans nearing completion that will also be mixed use. The 12 complex with the condos over the hotel will have ground floor retail as well.
Current Knight Stadium has long sloping stands and huge concourses. Do not expect that here. These will be steeper stands, and the 2nd deck will be covering the lower level more, and have more seats.
UD