There are instructions for dehydrating just about any fruit or veggie in the Ball Blue Book that I have. I'll dig it up tomorrow and post some of the ones you've asked about. I also have lots of info in the Excalibur book that came with my dehydrator.
After you’ve powdered the veggies, put them in a jar, do you vaccum pack the jar? I’m thinking of getting a dehydrater, Excalibur. You who have these really like them. Have you tried corn? I’m ready to begin some seed for the winter garden..wish me luck. LOL