Check the manual and it should be a home job- or if your LBS is friendly and you buy the spings from them- they should only charge a nominal amount for changing them. Only thing I found was the rebound rate offroad. I set it up to slow and it improved the fork no end.

On the fork flexing. The only way is to ride it. We only had a problem when we became really aggressive over rough ground, and as yours is a better fork than we had,(We had QR Fixing) I don't think flex will be a problem. Pic attached is of our Boxers, but look at this type of front fender. Stops a lot of mud from the wheel in the pilots face.