Welcome to the Q&A Forum

I think in this case you're fine using a 302 since you don't need to pass any pagerank onto the shopping cart. It can be considered a "temporary" redirect in some ways because you're redirecting the user to their own shopping cart, which changes for each user.

This. In the world of ecom SEO, do all you can to point people at just one page. Works better for users, and for search engine ranking. The only edit I would have is be very careful when configuring your URL's in the parameter tool. If done incorrectly it could harm your site. If you are having issues with multiple URL's getting indexed, then use htaccess to send bots and users to the correct pages. Same warning as above though.

You could consider using a different CDN set up. You could use something like MaxCDN and host them locally and in the cloud. That way you would have direct access to the images on your server as well for pinning and other social media purposes.

It might be that Moz's crawler is not picking up the description because of the way that you have it written. The standard way to write a meta description is like this. name="description" content="Buy the robust and reliable Canon imageRUNNER 2525 from Copyfaxes. Learn more about the Canon 2525 before you buy." /> You have yours written like this. http-equiv="description" content="Buy the robust and reliable Canon imageRUNNER 2525 from Copyfaxes. Learn more about the Canon 2525 before you buy." /> Using http-equiv actually tries to simulate meta information through a response header. Which is incorrect. You should rewrite your descriptions to be like the first type. Search engines might be able to decipher it, even though it is semantically wrong, but I would not risk it.