Are you asking how to get people to find you with their phones? One way is to have your QR code available for people to scan it. You can place it on your van, website, cards.... wherever. You can make the QR code take them to an offer on a webpage or whatever.
John, mobile websites are super easy to set up. Whoever did your website ask them. If you did the site yourself on something like godaddy. You should have the option to also make a mobile site.
Yes, you can run a google adwords campaign mobile only.
Super niche but super cheap also, from some people i have spoken to dont expect a lot of jobs but the return can be good.
I admit, laughed at it also at first but after some research it can be a good guerilla marketing campaign.