The Ghirardelli melting wafers are a compound chocolate, meaning the cocoa butter has been replaced with vegetable oils and waxes. You do not need to add paraffin to them, and you do not need to temper it -- just melt and go.
If you were using chocolate chips -- which are manufactured to maintain their shape and usually of a lower quality chocolate -- a bit of paraffin helps with the overall look and texture.
If you were using premium, coverture chocolate, you would need to temper it. Simple melting it would result in an inferior finished product.
I think you have made a great choice. Compound chocolate is much easier for home cooks to use, and the better brands (such as Ghirardelli) are far superior to Wiltons.