1. Somebody else had mentioned this and I am working on it. Currently, the list of charities will show up when you create the survey and you have to select 5 of 20 charities.
2. This is a great suggestion. I wil A/B test whether Register or Sign Up gets more sign ups to be able to decide which is better.
3. Product based incentives are a great idea. I am not entirely sure how I would implement that though.
As for skewing the survey pool, I would argue the pool is already skewed towards people who either love or hate your product.
I think the charity component skews it less because the act of giving your time and opinion is very similar to the act of giving to charity. Hence, more of your customers can connect with that charitable act than say, entering a drawing for a prize.