"Do you really believe that free schools are likely to solve any of these potential problems?"
No, I didn't say they would. I think the free school policy is fraught with problems. However, it's the only way to set up schools at the moment. In my area new schools are needed because the existing ones have already expanded, or are in the process of expanding, to capacity, so your "instead giving them a bit more money to expand" option isn't possible. The numbers are too big.
"How is letting inexperienced, unqualified people open schools in buildings which are not purpose built and have no requirement for outside space going to tackle those issues?"
I've only seen experienced, qualified people opening free schools in my area so far, in buildings that have been adapted for the purpose. I'll wait for their Ofsted reports before making judgements on their success, but I haven't heard any negative reports so far.