Yes there are Entertainment agencies that the bigger groups, DJs etc etc use for this type of visa, unfortunately person i know used to do this passed away so dont have any contacts in that space. Suggest google and contact all
You can start a buisness but you cannot work there. For that you require a different visa and work permit and comply with everything that goes with it.
Lots of teething issues with it at moment, cannot enter thailand as place of residence so cannot put a thai telephone number in hopefully have all these issues sorted before it starts.
If it is like Singapore & Malaysia you dont show anything the IO will know if you are registered or not. This should hopefully end up like Singapore and Malaysia where they are automated entries as well now. You got to look at the bigger picture