1, are you looking to develop your own or are you looking to use a commercially available software package? The latter is typically called PSIM and there are a handful of vendors who do this (though most charge hundreds of thousands for this).
Related: Why PSIM Will NEVER Be Popular
IPVMU Certified | 05/09/16 05:23pm
I am not sure if these guys would do what you are looking for. However, you should check them out. They have many integrations. We've never worked with them, but I have spoken to their US reps on several occasions and found them extremely helpful.
I haven't studied it and have only briefly seen it in action as a box running Exacq, but Tyco/Kantech Intevo is supposed to do all of this.
There are many companies who offer integration between their own access control, alarm and video.
#1, do you already have products you want to integrate together or are you open to choosing 3 new products from one manufacturer?