Where is everything stored

Warranty Hero 2 manages your database for you

You can find the database, images and receipts in this path:
~ > Library > Application Support > Warranty Hero 2

Update:
Since version 2.0.3 Warranty Hero conforms to sandboxing. This means your data is stored here:
~ > Library > Containers > com.nodheadsoftware.WarrantyHero > Data > Application Support > Warranty Hero 2

~ is called the tilde sign, it stands for your user folder.
If your name is Tim, it would be like this:
Tim > Library > Containers > com.nodheadsoftware.WarrantyHero > Data > Application Support > Warranty Hero 2