I would extend the 4 hour rule to Obligation rolls too. Force dice aren't that big of a deal because of the way they refresh the other side's pool with use. But Obligation should change at the same pace as session talents would refresh. Having obligation issues for 8 hours is a little rough on one PC and too much of a relief for others.
As someone who has dealt with the vagaries of international shipping professionally in the past, it doesn't surprise me that we occasionally have to wait while a shipment is delayed.
It surprises me that they get it right most of the time!
Seriously, when your freight is one container amongst thousands, it boggles the mind how many things can cause delays.
That's why those few boxes that were airfreighted to GenCon were so special!
1) As above, players can make any choice they wish. As a GM you show them the cost or consequences of their actions. If they end up killing innocents, everyone from the local law to the general populace will quickly turn against them, or it might result in a bounty on their head (Obligation).
2) Yes, you can (and often must, regardless of your SW knowledge) make things up on the fly. The key is to keep the Star Wars feel in anything you make up. In other words, call it a XJ-38 Sand Speeder and not a Megacorp Hovercraft. If you keep the Star Wars feel, your players will never notice.
3) Yes, and yes. This is encouraged. If you see a possible plot hook that's cool and ties into the background of one of the characters - go for it. They'll have more fun and you'll have more fun.
4) Not really, especially with this system. The story can be mostly in your head, though some GM's like to have copious notes about the plot - or use published adventures as their "notes." Keeping a few key adversaries tabbed in your rulebook prevents you from having to keep too many notes there. Other than basic housekeeping (initiative order, etc.) just jot down a note or two as ideas for furthering the plot occur to you.
5) If you're in the middle of a combat or scene where position is important, then take a picture of the table. We assign one player the job of taking notes during the session, which is then appended to a Google Doc. This not only keeps track of where we are, but also is VERY entertaining.
6) Tricks? Ham it up. Be overly animated. Use accents. Use body language. All of this will make your NPCs memorable. Challenge your players. Make sure that they feel the risk and feel they their successes (and failures) are close, hard-fought battles.