What bluray hardware/burner should I buy?
Up to you, but Adobe recommends Digistor-Panasonic drives (Panasonic hardware is what Digistore uses in their enclosures). I've been using an LG internal drive in my Mac Pro for at least a few years now. No problems with it. Here's a page of external burners.
(Is a "Plugin" the hardware?)
No. The plugin is a secondary piece of software you need to purchase from Roxio to burn Blu-ray video disks. Without it, you can only burn Blu-ray data disks.
The drives are generic. It doesn't matter what platform you're using.