What legal issues did you run in to? If I started up the site after the sale (I live in the US) would the site just get taken down for breaking some laws? Also were you able to run the site yourself ( I have a lot of sysadmin experience) or did you have partners?
Replying from my cell, please forgive any typos.
I settled with the SEC for running an unlicensed exchange. Presumably you could build on it and license it, but I am not a lawyer and you would definitely need one familiar with the SEC and securities law.
I was hoping to utilize it for a JOBS act compliant platform when they finished setting up the guidelines, but then the settlement ended up having a two year ban as well, so I am not allowed to work on anything securities related for two years. (And even then, it seems unlikely they'd approve me unfortunately.)
Another option I looked into was using it as a platform just for accredited investors. Working with accredited investors alleviates many of the restrictions. (And in theory you could vet investors just by having them sign a message on the blockchain from a sufficiently large wallet. Again, IANAL.)
Other options for a US citizen would be to convert it to a currency exchange, or online wallet service.
Non-US citizens it will vary country to country, but in general my research leads me to believe many places in the world enjoy far more freedom in this regard. Consult a local lawyer.
As for operation, I had a full time job while I was running it. I built and operated it during evenings and lunch breaks. If you don't have help you will want to have constant email and system access though to watch for hack attempts. The code sends emails that you will want to act on periodically. (Eg, to block IP's or ban users.)
I hope that helps.