Can I show my product ratings in my ads?

Yes. But we currently don't recommend adding product ratings to ads.

What if a campaign is not spending all of the budget?

It's possible the impression share loss due to rank includes losing out on impressions that the campaign is eligible for but are very broad so you would not want to show for them anyway.

What do you recommend for a new product launch?

If you are launching a new product, there are a few ideas to get it out there.