No integrations are needed for supported non Qolsys window sensors if the panel has the supporting radio band. With IQ4 you purchase the bands and cell platform you want.
Ah, that sort of explains it. There's nothing special about ADT, except some perceived value in the name. People see ADT in banks and commercial installations and think they're getting some premium security system in their home. What you end up with is an overpriced rebranded security system and an expensive contract. The Qolsys panel though is a very good panel, at least they got that part right.
Unless you mean that literally, the panel is probably fine. I'm paying $26/month for monitoring. If you can get the dealer code for your panel (try 2222) then you can install better sensors and choose a different monitoring service. PowerG sensors are rock solid, inherently long range, and don't operate in wifi, zigbee or zwave bands. I would never in a million years trust my home security to anything running on Zigbee.
What I recommend is go over to the Surety site and ask for help determine if you can take over the device. They are very friendly and helpful and can tell you with some info you pass them privately.