Hi Mary

I play Irish music on a variety of stringed instruments. Yes you could tune your 5 string instrument to DGAE if you change the strings, and you may need a capo to get it right depending on the length of the neck on your banjo. A mandolin tuned GDAE would help you get the fingering for Irish tunes although you might find the extra stretch on a banjo difficult. You could then go on to the fiddle! I play an Irish Bouzouki tuned GDAD which sounds well you could also tune a mandola that way or like a banjo or banjo mandolin GDAE. The fingering on all GDAE tuned instruments is the same. Get tuned up and have a go - and good luck

Herge