Ok this could be a fun one.
Firstly let me start with saying that nearly all source units that are double din with a screen these days are reverse camera compatible.
Fairly easy to check.
Allot of people have done quite well with units from China/Taiwan and some have had rotten luck. Just a quick note on these, although you may see a couple of different ones on ebay that LOOK identical yet are vastly different in price, let me just say that they are usually not the same internally.
I am normally one to say stick to the brand names, but again it can be a bit of pot luck. Most brand names have set deals with mapping companies and can be a pain to upgrade to off road mapping. Not impossible but it can be annoying.
Out of all my installs I would say that I have had the least amount of problems with pioneer. The down side to pioneer is that to get a navigation compatible unit here they cost a heap of coin.
As to fitting a unit into a Patrol, It is very easy to do. The cover that surrounds the radio usually has two screws then pulls out with clips around the side. The only thing to look out for when installing a unit is that you will have to run a new earth as they are chassie earthed factory.
If you look at my build thread it shows my install in my 08 patrol, that could give you some ideas if needed.
I would say to stay away from Phillips, as I have had nothing but problems with the navigation software in them.
If you want any more help with it feel free to send me a PM and I can run through it all if you want in regards to options that are due to come out or where to buy from if you want. Also if you want to install it yourself I can send through detailed install instructions for you.
Cheers
Evo