Keep in mind I have only been heli skiing for one day but I am used to skiing in pow and in western Canada.
1 - If you can ride pow on a blue run you will be fine. There will be options to go steeper but you will pick it up quick. IMO it hard to ride ICE than deep pow.
2 - Don't know about the company sorry.
3 - When I went I rode my NS titan 160. It was fine. Just set your bindings one back from where you would normally have them. I have ridden plenty of deep pow on my 155 Evo with my bindings centred. You will be fine. Most companies usually have a Burton Fish or something powdery that you can rent if you are worried.
4 - I would not worry about the pants thing. You might get a bit of snow up your back but it will keep you cool!
5 - I have loads of stuff with my gopro. IMO the stuff that works best if the one on the end of a collapsible ski pole. You will have a back pack on as your avi shovel will be in there. So get one of these and a helmet mount and mix it up. Just don't do it on every run otherwise you will focus on that and not on the awesomeness!
6 -You will be doing less runs than normal but you will be working harder. I knew a guy who worked for a heli company and he said this is the most important factor. You want to make sure your legs can handle it. As I said above you will get the pow part in no time but if you are unfit your body will end your trip before you ability does. Start hitting the gym!
7 - Your mate is correct. They will give you the training you need. It doesn't hurt to do a bit before you go out there. I think snowolf has some sticky threads in the Back country section about web based avi training.
Do you realize that you will be ruined for all resort riding after this!