Apparently, manpower/ labor costs will be high cos you have to hire staff to go down to negotiate deals with sellers/ shops/ retailers. Then need writers to write those deals in a nice way and post on the site.
You need to get your facts right before you start talking nonsense and embarassing yourself. One billion dollars?? http://en.wikipedia.org/wiki/Groupon Groupon was started with seed capital of only USD1 million
Anything over $10 is beyond the scope of the majority of DP members, IMHO. I just wouldn't get your hopes up for much better answers
It depends on how much you want to outsource, you could easily set up the site yourself and just have to pay for the domain and hosting, but then you need to fully manage the website yourself. It's a much better idea to setup a startup capital, then write a list of things your startup capital needs to cover, then go ahead and start using the money to meet your goals. Obviously it's going to take you good few months to see any results from a website like this, a lot of time finding deals/coupons and to be honest, I can't see many retailers giving you unique discount codes unless your site is already huge.
Negotiating the deals ... this could need a man but you can do it as well. Saying you get this for 100$ and the deal is for 50$ can also do it. But who to ... ? I think the marketing costs should worry. On this depends your success or not.