Book recommendations would depend on what technology you intend to use. For example many people use Catalyst for websites, in which case there are a number of Catalyst books to chose from.
As for who uses perl for websites, a lot of companies do. For example if you take a look at jobs.perl.org you will see that booking.com have this open vacancy for lots of perl devs, so it would be reasonable to assume that they use perl for their website. There are plenty of others, and I have been approached by around a dozen of them, but they are more local in nature.