1st you need more RAM. 4 gig is not enough IMO.
These are the most basic questions all covered in the getting started guide and in the manual ,you should take some time to read up.
The CPU meter is not very accurate I use activity monitor.
2.8 Quad Intel(2008)MacPro24 gig ram,OSX10.83, DP8.01, RME FF 800,Great River ME-1NV preamp,Rode NTK and AT4033 microphones,NI Komplete 5,6,7&8U,,Arturia,Spectrasonics, IK etc & many more VI's and plugs... Vdrums (TD20 expanded) Superior 2 etc..., Focal Twin 6 monitors, Shunyata PowerSnakes and Conditioners,too many hard drives... ESATA