This is a great idea.
1) get your full license
2) know your program's rules for moonlighting.
3) if there is no mention about opening your own practice, then ask and find out if they approve it.
There are several residency programs that permit residents to open their own practices.
One example at MGH psych for PGY4s:
http://www2.massgeneral.org/allpsych/adultresidency/program.htm
"Moonlighting opportunities and the ability to start a private practice are available to PGY-4 residents."
4) It is easier as others pointed out to use another docs place/practice, etc.
5) You won't be able to hold yourself as the specialty you are training in because you haven't completed the residency yet. So you will only be able to advertise as a general practitioner who is focusing on OMT.
6) you can easily say you will only do OMT and not be a primary care physician. However, as others pointed out above your medical background will hold you to greater expectations of working up a back pain that could be prostate CA mets...
7) EMR is easy. Use microsoft word or adobe. Have your fax be an internet based company and your phone be through skype. Then all you need is a good lap tap with mobile internet and a few hard drives to back up the medical charts. Even after you complete the residency you would still need to keep the hard drives with the charts for a certain amount of years. Different states have different requirements for how long records need to be kept.
That's a great idea, very doable, but contingent on your program directors approval. Best of luck.