I haven't worked with this myself, but have you tried escaping the special characters in your classification mapping?
So instead of:
2.4 Ft Bump ‘N Go Chucky Animatronic - Decorations
try
2.4 Ft Bump \‘N Go Chucky Animatronic - Decorations
and instead of:
Ghost Face ® Call Me Double Sided Fleece Blanket
try
Ghost Face \® Call Me Double Sided Fleece Blanket
or maybe even try the encoded version of this character with:
Ghost Face %C2%AE Call Me Double Sided Fleece Blanket
or
Ghost Face ® Call Me Double Sided Fleece Blanket
or
Ghost Face ® Call Me Double Sided Fleece Blanket
I don't know if that will work, but you can try...
In the medium term, I don't know if you are asking "technically" how to switch to using SKU (in which this is really just passing the SKU into your products list, in the product identifier position), or if you mean, is there any sort of prep work involved before making the switch... In this case, I would think (and again this depends on if you get the short term solution working) that the sooner you make the switch the better... I can't think of any prep work... I think it will be a matter of pulling off the band-aid...
As for Long Term, I don't use the classification importer much myself (I don't have a lot of long specific lists to classify in my implementation), but I believe that you can connect it to FTP, and newly uploaded files will trigger the classification importer...