Electronic Alarms and Home Security Devices - Ademco Lynx repair/upgrade

Hi! Terrific forum here. I'm so grateful for any guidance you can offer.

I bought a house with an Ademco Lynx-R (professionally) installed by the prior homeowner. I've thoroughly read the installation manual and I have a few questions.

1) I broke a window transmitter and tried to install a new one. But it appears the OEM default installer code has been changed, likely by the ADT tech who got the system running when we first moved in. ADT gave me quite a run-around about restoring that code -- i.e., transferring me to offices all over the country until I gave up. According to the installation manual, I can restore that code by powering down and going through the *blahblahblah-within-50-seconds stuff on the keypad. Then I should be able to delete the old serial number and input the new one. And life should be good again.
QUESTION: If I power down the panel, will I need to reprogram all the zones? Won't powering down the panel tell ADT that something is going on, and in the midst of this kooky operation I'll find a (handsome but mildly annoyed) SWAT team on my front porch?

2) I've picked up a bunch of 5800 series geegaws that I'd like to install. I understand many of these devices need their own zone, and some need more than one. If I'm reading the manual correctly, I'll probably run out of zones.
QUESTION: I want to buy a receiver to accommodate all the new zones, right?

1) Use 6321 as the installer code and you won't have to worry about it :D
And, no, powering down the system does not de-program anything - it has a non-volatile EEProm memory.

2) You can't add any zones to an Ademco Lynx system - even with another receiver. It is what it is. Sorry.

If, for some reason, the 6321 doesn't work, then you can use the power cycle option as you mentioned.

Good luck!

Oh, boy! Big thanks for the tip on the installer code. I'll let you know how it goes.