Changing Accenta G4 Alarm for Ring Type Alarm

I currently have an Accenta G4 alarm that has 2 door sensors, 1 motion sensor and the outside alarm box, all hard wired.

I’d like an alarm system that can be remotely managed on your smart phone, getting notified when it goes off, being able to switch it on/off.

I’m assuming that I can’t do anything with the existing setup to enable me to have that facility? So I’ve got the option of leaving everything connected in place and placing the motion sensor in a different corner of the room. Or is it easy to disable the alarm and remove the motion sensor so I can put the new one in the same place?

Also I had to change the battery recently as the alarm kept going off if there was a power cut. Is it possible to put the alarm is some sort of maintenance mode so that if the battery goes flat again in the future it doesn’t do this again?

For info I’m looking at the BF deals that ring are currently doing. Hub, 2 door sensors, 2 motion sensors and interns camera for £150. For the money is this a decent enough setup?

Thanks