CD audio quality depends on the individual recording and source. If it's from Decca, RCA or one of the major labels, they are usually nicely cleaned up from masters, if it's from a radio show consider the source, but some odd small labels (or older issues) are mastering from records or old tapes and show the scratches or hiss. It's hit or miss, but I'm happy so many of these have found their way to CD at all.
Randy would be doing a great service by liscensing these tracks for a proper Disney release, since they seldom ever issued many of these songs on Disneyland/Vista anyhow. But so far, Disney hasn't liscenced Disney tunes from other labels - I wish they would.
In the meantime, a good place to start is the RCA Zip-a-Dee-Doo-Dah compilation CD, which is entirely made up of Disney-related RCA recordings of that era.