Glad you've found us !
Loads of questions, I'll try to help a bit:
JonesTheSteam, we're very inclusive here - and most of us started with run/walk - I could scarcely stagger to the next lamp-post when I started but soon improved, stick at it and try to enjoy yourself.
Futurity, hello ! Saggar is spot on, try to eat your ordinary breakfast when you get up so there's plenty of time to digest it & pop to the loo. If you're too nervous to eat, it wouldn't be the end of the world for 5k but you'd need something to eat & drink as soon as you finished - not a recommended strategy for anything longer though.
Crunchie, you know you'll be fine, your training times have been great - and better than you expected , have a great run. Carry a water bottle with you all day on Saturday and make sure you use it & refill regularly.
Moondog, go for a run outside, don't take any gadgets, just run as you feel, preferably with a faster friend, you'll be amazed how well you've done when you check the route out later in the car An hour is a respectable time for 10k, you won't win prizes but you'll be a long way from being last, typical back marker times are 1:15-1:25.
Last but def not least, Quanglewangle, gradually increase your distance, don't worry about speed, that will come later. Rule of thumb is never increase your longest run or your weekly mileage by more than 10% at a time. Pick up steadily, and every 4th week cut back (by up to half) to allow your body to adapt to your new training.
Ooh, just checked out World Masters Orienteering site - sounds like fun !