Ok Vajih102 a long explanation then...
I installed tilt sensor basically for two reasons. 1, if someone tries to steal wheels, for which he would have to use a jack to tilt the car up. 2, if a car-lifter start to tow my car (by this I do not promote illegal parking, but you never know). Its cheap, and basic function is because of mercury, as it conducts electricity. Click below to see how it works. Its self explanatory
How tilt sensor works - animation
So, when the car is tilt, the remote gets the strong vibration, and its LCD shows the tilt animation.
Temperature sensor came with the system, whenever you communicate with your car, the remote shows the current temperature in your car. By A/C controller, I mean on and off only. I don't have those expensive automated climate control systems. With a small thermostat set to 30 degrees threshold, I got one wire from that sensor towards thermostat and gave current to A/C switch. This means if you are shopping for groceries, and your family/friends are waiting in car, I assume your car fan was running, and the moment it gets hot over 30, A/C switch turns on automatically. To turn this feature on and off, I have got a little switch beneath the little pop-up box (right side below of steering wheel).
Door opener was very simple to do. To tell you the truth, when I was playing with auto-window unit, I found a glitch in window closer system. And now I use it as a feature. If I press the unlock button on remote, car door unlocks, and if I press again and this time keep it pressing for 2 seconds, the driver door opening handle pops up, opening the door. I was surprised to see that each door has a motor with the door opening handle, and if there could be more buttons on remote, or combination options, I would have easily open the remaining 3 doors. The use of this feature is pretty useless in my opinion, besides just one, which I figured helpful in a scenario, when your hands are full with groceries or stuff, and you can't really reach the door handle to pull, but can trigger remote. I once did with teeth :-#
Emergency brake thing is just what you will do with CPU. There is a small Jumper settings, and all you need as an optional device to engage this feature is an old hard drive jumper This will put the car in emergency brake if you have remotely started your car, and have carried on with driving without inserting your key in. Happens automatically on 2 wheel revolution. Also alarm sounds off loud.