Howdy Emceey...(you could do with using some paragraphs
)
As a beginner, the McMillan running site is a decent outline of what paces you should be doing.
http://www.mcmillanrunning.com/index.php/calcUsage/calculate
i don't deal with km, but from what you say at the moment your 5k is in the 8.35 to 9.15 mins per mile range
And your easy pace is in the 10.28 mins per mile domain
Using your fastest 5k race pace, I'd say your 10.28 is spot on for your easy pace. I'd put the range as being around 10.20-11
Using a rough guide, on what info you've given, i'd work out your paces as follows
5k pace 8.35
10k pace 8.50
tempo (pace you can hold for 10miles in a race) 9:00
half marathon pace 9:05
marathon pace 9:20
steady 10
easy 10:20+
Not to bamboozle you, most of your mileage should be at easy pace. It depends how much mileage you do, how much you can dip into the other zones....you need enough supporting mileage....