I noticed some thick mud/grease and I had to wipe it off, is their anything that would take it off without scrubbing? Is their anything I have to watch out if I sprayed the undercarriage with a power washer at high power?

Just go to a spray-it-yourself car wash... Spray some GUNK on the heavy grease deposits, wait 10 minutes and power wash everything... Everything underneath is safe to power wash...

If you power wash the motor, just throw a plastic baggy and a rubber band around the distributor cap and ecm... After that follow the directions above...