Of course lot is for traceability but it is the first level. It tracks just the lot.
If you want to add the production tracebaility (when some lots are merged in a new lot), we need to have a view like discussed here: https://groups.google.com/forum/#!searchin/tryton/traceability|sort:relevance/tryton/6fSdXWDSe9M/ylj-F_8RAwAJ
No, this is clearly a product (or variant) with a product code
Here the argumentation is about the fact that serial number or lots are the same. It is only a matter of limitation on the quantity.