Accounting for 2 & 3, and the team they work on for 1. I dunno how big a company you need to be to need a single full-time HR person, let alone a department...

Accounting for 2 & 3, and the team they work on for 1. I dunno how big a company you need to be to need a single full-time HR person, let alone a department... 50, maybe? HR are what would be called in the military REMFs. Most corporations I've worked with have an order of magnitude more "support" staff than people who are actually doing revenue-producing work, and the bigger they are, the more wastage of this type they can afford to support, which feeds upon itself to produce yet more management and ancillary positions.