Google the model number on the brain box itself
Find a PDF of the manual
Read it

I have a Viper 791XV... I disconnect the battery all the time... it's fine
When the remote battery dies, I just pop a new one in... it's fine
You can still get into the car using only the key, but the alarm will probably go off. With my car, theres a procedure to disarm the system using the Valet button (black button, hidden somewhere in the car).
These answers are specific to my set up only... yours may vary.

 

I need to find the alarm box then and go from there.

 

good alarm ++