Have a search on the UK Kawasaki forum on stuff on the GPZ500S (same model as the Ninja 500R)
http://ccgi.wwwtechs.force9.co.uk/phpbb2/index.php
There is a fair bit about living with the bike everyday. Bear in mind that UK gallons are more than the US gallon for gas mileage. US gall = 3.785 litres & the imperial gall = 4.546 litres. I was averaging 60 mpg with mixed riding.
I was doing a 35 mile each way commute on the 500 on fairly twisty roads & found it ideal. You will find that you can't corner as quick as the 6R & you have to use the gears & revs more to make rapid progress but it is quick enough under most conditions. I did find it a bit cramped (I'm 5'10") for my legs but acceptable for the trip I was doing. Brakes powerful enough but then mine had twin front disks.
I got the bike from new & the only problems were a duff starter solenoid which was replaced under warranty, aftermarket immobiliser which had to be replaced & the rear suspension bushes & swing arm bearings needing replacing after 15k miles but I reckon this was coz the dealer did not lube them, as quite a lot of basic stuff was neglected by them.
Otherwise I replaced the chain & sprockets at 12k due to the conditions I was riding in & tyres lasted about 4-5k rear & 8k front. Used Bridgestone BT45's after the original Dunlops (adequate) wore out & the BT45's were far better especially in the wet.
If used in all weathers the swing arm & exhauts get rusty. General finish is adequate but not brilliant, certainly better than Suzuki GS500. I fitted a front fender extender to keep crud off the engine & squirted WD40 in the indicators to stop them rusting as water got inside them. If used at night I recommend fitting a 30% brighter headlight bulbs, makes a noticeable difference. Mirrors not brilliant, you either have to move your elbows or get extenders to space them out.
On bendy roads it will spin along quite nicely at up to 75 & will hold 85 on our dual carriageways with no problem. Keep the chain adjusted for smoothest gearchanges.
I found the 500 a lot of fun & undemanding to ride unless you were trying to keep up with a 1000cc bike :squint Power is enough to make you grin when it kicks in at 7k rpm, somewhere between the Suzuki GS500 & SV650 in comparison.
HTH