Can you discard inactive jobs in Firefly
Yes, you can end up with more than inactive 3 jobs in your hand after dealing, but you must immediately discard back to down to a maximum of 3.

Basically when dealing you consider 3 cards (these cards are not counted as being in your hand yet while you are considering them). You then select a maximum of 2 of these cards to keep depending on which ones you like (the selected cards, if any, are now placed in your hand). Then you must immediately discard back down to a maximum of 3 cards (so you would discard jobs you previously had that you didn't want to keep).

The FAQs hosted on flamesofwar.com are the official ones as they are linked to from this official page, although the version you linked to (v2) is outdated, the most recent FAQ is v4.1.