No, donkies cannot play banjoes because they don't have fingers for strumming.
Duelling Banjoes
I would look for a store, maybe in a big city, that specializes in banjos and acoustic string instruments, and give them a call.
AskOxford, the definitive reference source for the English language, lists both banjos and banjoes as the plural.The plural of banjo is banjos or banjoes, both are correct.
banjo, bijou, banjos, bijous, bijoux, banjoes, basenji, bejesus, bejewel, bluejay, banjoist, basenjis, bejabers, bejewels, bejumble, benjamin, bijugate, bijugous, bluejack, bluejays, bootjack
The plural is the same as the singular. Since the pronoun you is the person or persons you are speaking to, he, she, or they know which you mean. Examples: Sarah, you saw the banjo on the table. Sarah and Sam, you saw the banjo on the table. Everyone, you saw the banjo on the table.
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 2 words with the pattern -A-JO--. That is, seven letter words with 2nd letter A and 4th letter J and 5th letter O. In alphabetical order, they are: banjoes mahjong
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 2 words with the pattern -A-J-E-. That is, seven letter words with 2nd letter A and 4th letter J and 6th letter E. In alphabetical order, they are: banjoes hadjees
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 2 words with the pattern B--JO--. That is, seven letter words with 1st letter B and 4th letter J and 5th letter O. In alphabetical order, they are: banjoes bonjour
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 5 words with the pattern --NJO--. That is, seven letter words with 3rd letter N and 4th letter J and 5th letter O. In alphabetical order, they are: banjoes bonjour conjoin donjons kunjoos
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 5 words with the pattern --NJ-E-. That is, seven letter words with 3rd letter N and 4th letter J and 6th letter E. In alphabetical order, they are: banjoes bunjees bunjies conjeed conjees
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 1 words with the pattern -A-JO-S. That is, seven letter words with 2nd letter A and 4th letter J and 5th letter O and 7th letter S. In alphabetical order, they are: banjoes