As long as you aren't altering the hostname or IP addres of the ePO server you should be fine. If you are then I'd recommend diving into the Knowledge Center. There are articles on both that you can find there,
The only area you might have an issue is with your connection to SQL server. Assuming you use the SQL express option then that's fine. If you aren't then you need to make sure your SQL Server has a trust relationship with the domain your ePO server belongs to.
this will work just fine.
nothings wrong in migrating it to the domain.
just be sure that your ePolicy server IP address will be added to your clients DNS.