If you are going to use air tools like a DA, palm sander, strait line file, etc you will need a 80 gal and twin cyl that puts out some air. Also that bigger thank helps keeps on the moisture but like said it needs to beset up right with dryer. Good compressors and high end guns are not cheap. It not that you can not get by with less, depends on what you want to do and want to spend.
You can get it done with a $300 compressor and $40 gun also.