Gear is correct - Caddx or DSC.
I have a DSC (Caddx was too expensive for me) , and it works well - 64 zones. Don't put all your doors on one zone - how will you know where the breach is?
Wireless door contacts are expensive, cheaper to wire in.
My opinion on wireless sensors is that it only makes sense if it is to avoid the running of expensive conduits outside - i have wired and wireless outside PIR. The wireless are for where i would have been charged thousands to dig up concrete and have long runs to outbuildings and pole mounts in the garden etc. Wired outdoor PIR if they are installed on the house walls.
Panic buttons are super cheap, might as well have a few scattered in the house.
I have the small 7ah UPS for the sensors, and then the panel has 2 x 7ah batteries for backup.
I bought the system myself and had a 3rd party installer do the work - came out at less than half what Blue Security quoted. I just called them once it was installed and they came and installed the radio for monitoring.