I can’t disagree with any comments.
Might I ask in what State are you located?
In Texas you have to be an NRA Pistol Instructor to be
a CHL instructor. But that is just Texas.
NRA except for a few courses is about imparting Knowledge, Skills,
and Attitude to safely enjoy the shooting sports. It is a somewhat different
mindset than CHL which is about personal protection and the laws of the state
pertaining to the carrying of a deadly weapon and or a concealed weapon.
A Texas CHL class must be taken in Texas for it to be valid.
NRA classes can be taught anywhere as long as NRA guidelines are followed.
These are not hurtles, they are just considerations you might want to think
about before making your decision.
As far as insurance goes, save yourself a lot of time and get the NRA Instructor
insurance. It is the best I have found and really inexpensive for the coverage.
It will also cover you for classes you give that are not NRA classes.
If you get into firearms instruction, one of the certificates you will need is
the Range Safety Officer (RSO) or even better the Chief Range Safety Officer (CRSO). You can Get these through the NRA.
This will help you at whatever Range you use.
Wish you well in your endeavors and if I can answer any questions give me a line.
Good Luck.