Hey there, Camille...
My recommendation is to come in late July or early August when things are in full swing on the Island. There are actually more than six different ceilidhs and musical events happening every single day throughout those two months. One of the more central points for enjoying as many ceilidhs as possible would be in the Stanley Bridge/Cavendish area as there are tons happening out that way. That puts you in close proximity to lots of great food options as well. You’ll need a car in this area though!
For walkabouts, Charlottetown is the place to stay. I’d highly recommend booking something there soon and using that as your home base. Charlottetown music and food culture is incredible and there’s so much happening in July and August. You can either use the online booking tool on the website to find the lodging of your choice, or call Tourism directly 1-800-463-4734 and the staff there will help you.
Hotel on Pownal would be my recommended spot in downtown Charlottetown, especially if you book soon! Popular spot!
To see a full list of ceilidhs on PEI, check out that link - there is all the info you need for every single one happening (worth going to!) throughout the season.
Another great spot to check out things that are happening would be The Buzz - PEI’s arts and culture magazine. You can find paper copies almost anywhere on PEI, but they also have a great online directory.
Hope that helps!