keywords and meta-tags

Have you already had a book published in the store? If so, can you tell me:

1. Are 'keywords' in IBA (entered in the Document window in Inspector) the same as meta-tags?

2. If so, how long does it normally take for them to be processed so that they work as search terms in the store?

3. If they are meta-tags, is it possible to edit them after publication? The editing options in ITunes Connect (under Books > metadata) do not include 'keywords'.