Slow Cooker questions

My husband and I just bought a slow cooker - Hamilton Beach 6 qt Stay or Go (https://www.google.com/shopping/produ...)

and an Indian food cookbook (http://www.amazon.com/gp/offer-listin...) to go with it.
I noticed the recipes call for 5 qt slow cooker, so my first question is does it matter if we use a bigger cooker?

Does anyone have experience with the one we bought? Is it any good? Should we exchange it for a better one?

Any recommendations for great cookbooks for slow cookers would be greatly appreciated!

Thanks!