I was taking a look at my first sale from the other day and I saw that with Clickbank you could contact the user who bought the product from your affiliate link. Would it help me get more conversions if I contacted this user and ask for a one paragraph review of the service they have received. I have no testimonials or reviews of my products on the site.
You mean your own product or products you are promoting? If it's your product, then give away free copies and ask for reviews. If it's someone's product, then you can create *fake* testimonials or take some from the merchant's sales page.
Why don't you look for testimonials for this product on other websites? You can always quote them and paste the link of the source to the testimonial with a smaller link. That's the easiest way.
I don't think that it's necessary. You can easily find 2-3 reviews on the Internet, without contacting anyone.
The Publisher should have collected several testimonials that you can use, that is if they are doing their job right.