The BoB (Breakout Box) is your I/O device. You can see it here:
http://www.pinnaclesys.com/productpa...&division_id=2
HDV is High Definition Video and is some way off in the UK from being anything useful (simply because people don't have the TV's to display it). It comes in various formats 720p and 1080i are two of them (the 720 and 1080 refer to the vertical resolution and the p is for progressive and i for interlaced). There are a few threads on HDV kicking around these forums.
All you will need to run two displays is a dual head video card. I run two displays with LE against my GeForce FX5900.
Plug-ins are small applets which you can "plug in" to your software to extend its features and functionality. These can be free or commercial. If you are using any for Studio then you can port them directly into LE.
One thing you should be aware of is that Smartsound is not supported yet in LE.