Legal Question in Business Law in California

As far as use of the premises -- probably not on the store's property. You might be permitted to do so on the public sidewalk. Of course, it depends on whether your merchandise is legal. I do not have sufficient information about that.

You mean, like giving out free samples? Maybe, so long as you don't trespass. The public is invited to enter stores like Wal-Mart, but the invitation is impliedly limited to those entering for purposes of shopping, and Wal-Mart can probably exclude people whose entry onto its property is to pursue a business and not to shop at Wal-Mart. You may also need one or more city or county business licenses, but that would be a local question.