You can definitely get keyless entry installed but its a bit too big of a project for someone totally new to working on automotive electrical work. There are no easy plug and play kits that I know of. I did a remote start and alarm unit in my car last November and it took a full day, coming from someone with a heated garage full of tools and a fair amount of prior experience with these things. My kit will also control door locks with the same fob but I now have to take apart all four doors and install the lock actuators, once I do that I just have to hook them up to the wires I left on the remote start/alarm kit and I will be in business.
So first recommendation, if you have any spare money at all, is to pay a local audio/car shop to do it. Chances are they will have their preferred brand they like to deal with and resell (ie, viper).
Second recommendation, if you are on a shoestring budget but still want keyless and alarm, you are going to have to find and befriend a "car guy" (or gal) near you who has some space, basic tools, and knowledge to do the job, buy a basic kit off amazon and get it installed on a saturday.
Camera is probably going to be a totally separate thing, are you talking a DVR that records while driving? A backup camera? A security camera? Either way, these things are typically separate from your keyless entry and alarm. Some of them have their own battery and you can just attach them to the rear-view mirror and charge them once in a while and thats all you need to do.
If you are going to be headstrong and try to do the keyless and alarm yourself, its not impossible but its going to be a big project. As far as the alarm goes there is just one wire in the car you need to hook to and it will tell your alarm box when ANY door opens, which is pretty great. The bad thing is the wire is super hard to reach. If you look at my remote start install thread I think I posted a picture of it...
The keyless part is mostly just door work and like I said I still haven't done that on mine but others here have some good posts on general how-to on installing door lock actuators.
You won't get through any of it without access to some tools and an extra set of hands, so if you don't have any DIY car friends in your area now would be a good time to start making some!