ok this is one of the sickest ideas for an app ive ever seen (except doodle jump of course). seriously tho its awesome, however there are a few key concepts with it IF you want to go through with getting this app made, its going to take a fuck load of work from you but it would definitely be worth it if you really commit.
firstly, you need to make this available to snowboarders as well because lets face it, there are far more freestyle and big mountain boarders than there are skiers (obviously you could keep this to just skiers but youre not going to make nearly as much money and itll be harder to get the help from companies
secondly its going to be harder for people to use it in the UK as we mostly ski in europe (basically in foreign countries). this means that with your concept of being able to upload videos and data live to a site that you choose for this app, its not going to be free, in fact its going to be fucking expensive to upload data. ive got an iphone and for an iphone abroad it costs 3 pounds per mb of data you upload or download. thats alot of money so people will be loathe to do that. maybe install a setting where you can store all you videos and data and then upload them when you get back home (obviously not a problem in the USA and canada because you'll still be in ur respective countries. something to look into maybe.
thirdly, i dont think the camera for an iphone is going to be good enough to keep up with action sports such as skiing, i could be wrong as ive never tried it but its definitely something you need to look into.
and lastly, ive had an idea for your outerwear problem which will be far cheaper than getting companies to design a whole line of outerwear designed for this. pm me about that if you want.