Marv - A good place to look for information on icebergs viewing along the coast of Newfoundland and Labrador is
www.icebergfinder.com. Yes, June is likely best. I would say the latter part of June to early July. Whether or not you need a boat depends on which way the wind has been blowing but there are a lot of tour boat operators along the northeast coast. Grounded icebergs are often accessible from shore. Come prepared for the weather. It could be just about anything but it there will be a chill in the air particularly if the sea ice is in close to the coast. You will want to be mobile so if you are renting a car you need to get a reservation pretty early as there is often a shortage in the summer.
Chuck