Convert old existing hard-wired system to Surety

I have decided to go with the easiest (and cheapest) solution for now as I learn more about the various systems at this property. I bought an ADC-SEM-300 and I am heading up to the property tomorrow.
I’m following these directions: How to Install a SEM 300 System Enhancement Module for Honeywell Vista

Questions:

  • Just confirming that I should be able to reset the Vista installer code without anything from previous owner / previous alarm company
  • When should I setup / activate new alarm.com account?
  • Other than the items / materials listed in the linked thread above, anything else I should be prepared to do to get the SEM300 installed, activated and the existing Vista system connected to ADC?