Is it possible to remove the "default site" from a MSM installation and then remove the MSM plugin, thereby creating a stand alone from the second site?
I'm running EE 2.7.2 with Multiple Site Manager
Another option is to duplicate the entire MSM installation, set site #2 as the default, then delete Site #1.
I wrote an article about this process while doing it in EE1, so while some of the specifics will be different the overall process would be the same for EE2:
Nope, you're going to run into a bunch of problems.
I'd set up two separate installs and migrate the data using DataGrab.
Good luck!