Tyre pressure I've come to work on the bike and found it a little spongey on decent corners

check with your local bike tyre shop as pressures although recommended can be amended to get better performance and road holding qualities
These people have the knowledge to give you the right pressures for that brand of tyre that is on the bike.

Either or a combination of both. Suspension set up, tyre pressure, wrong tyre size or type, style of riding???
Check your manual for suspension set up details and tyre pressures. Check out your steering head is tightened correctly. There are no leaks from your fork seals and if all is in order try ridind it differently (and safely) on bends.
If you have just got this bike recently, it could just be that this particular bike doesn't suit your style of riding. I have ridden bikes that don't "feel right" to me but other people have no problem with. Maybe let a friend test ride and see what they say.

Replace the tyre. The only thing that keeps you on the road while riding a bike is the tyres. If you have any suspicions either replace it or take it to a tyre repair shop and see if they will fix it. I would re-inflate the tyre first and leave the bike over night to see if the tyre is sound or not. It may just be a failed valve.

OK this ought to help you, I pulled it from this site: http://www.dirt-bike-tips-and-pics.com/dirt-bike-tires.html

Air pressure: When riding in sand or mud, lower the air pressure to around 10psi in the rear and 11-12psi in the front. This allows more surface area on the tires to contact and grip with the sand. For harder conditions on motocross tracks and trail riding over stones, branches e.t.c, inflate them up to around 13psi, 14psi max. If the air pressure is too low over hard terrain, you run the risk of causing a puncture or damaging the RIMS. Don't tighten the nut (on the air piece) to the rim. It's not meant to be tightened. Back it off to meet the valve cap once you've got the air pressure right.

Yup nice question. For any vehicle accurate tyre pressure will give you better tyre life, low running cost, etc. Here is a chart for car tyres click here.
For bikes i havent found any chart. basically in india rear tyres having 100/90 18inch maximum tyre pressure is 32psi. front tyre having 2.75P or 80/90 18 inch uses 24 psi pressure. and do check your tyre pressure twice a month.

The max pressure is on the side of the tire; look close. Set the air pressure to how you want the bike to ride. 20 lbs and the bike is mushy and soft and pretty squirrely on the corners. 45 lbs and the ride is like a rock. Probably 35 lbs is a pressure you can be pleased with.

That is normal, most motorcycles run different size front and rear tyres. My BMW has a 21" in the front and a 17" in the rear. The tyre you buy should match your riding style. Don't get a race tyre if all you do is communting, the tyre will wear out too quickly. Expect to pay $150 or so for a rear tyre, perhaps a little less for the front. Mounting & balancing is normally $20-$50 per tyre. Many shops will not mount a tyre you bought somewhere else, keep that in mind if you order tyres from the internet.

it doesn't look like the tyre is low. When I got to work and had a look the tyre seems a bit soft if you push and pull the tyre as if to check the wheel bearings the tyre seems to wobble on the rim. So I'm wondering if the pressure is right what is the norm tyre pressure on the back?,Id run that tyre 28-30 if it was on mine,,,