Hi Mina,

What do you mean by 'giveaways'? To join a JV program, best thing is to go to the home page here, click on one of the listings on the calendar and then 'JV invite'. You'll be able to sign up and get all the details.
As far as building your list, if you set up a special page to promote the product you are partner to you can indeed collect emails and build your list for during and after the launch. This is what many JVs already do.

All the best,

Felix