mach1canuck,
Visit this site before you make any decisions.
http://www.pablaster.com/
As a rule of thumb, the bigger the compressor the better. If you chose to get the bigger compressor (230V) you could run an extension cord from your electrical panel to your shed to power the compressor. Then again it depends on what the distance would be!
Don't know what the difference in the noise would be.
John