Yeah I've been using them since this summer for storing my grain I buy in large enough amounts that a small storage bin will not suffice.
They have lids, and all you have to do is ask an employee where they are.
However my first batch of buckets I just bought online. Shipping was pretty cheap as I recall. The lids are in the same location in the store.
The non food grade buckets you get at lowes or Home Depot I use to clean bottles, or equipment in.
And yeah if you want to have a secondary they would work great for that too, just drill a hole for your airlock in the lid.