I don't think they are "hosting" the ONE DAY USF CAMP on June 6. Harbaugh and his staff will be present to meet recruits at the USF CAMP. IMO. That's how they are getting around the NCAA.
No, it's a Michigan camp. There is no NCAA rule.
Feel free to download and read the PowerPoint linked in the second search result, directly from the NCAA website, especially pages 6 and 7: https://www.google.com/search?q=ncaa+rule+regarding+football+camps&ie=utf-8&oe=utf-8
There is a NCAA rule that hosted camps by a university cannot be outside of the state or within 50 miles from the campus if in another state. They can however be guests at other camps outside this radius, including camps by other universities (ours) and camps that various high schools set up (likely for them), but not the ones actually running the camps. This is a loophole that Michigan, Penn State, etc are using that the ACC and SEC (and likely Big East before) didn't allow their schools to use/abuse