When managing print colors via an ICC profile, is it necessary to also specify the correct paper type in the printer properties dialog? I'm using a Canon Pro-100 printer.
Yes, absolutely. In the printer properties dialog you must specify the paper type you are using and disable color management by the printer driver, as LR is already taking care of that.
Or specify "Managed by printer" in the paper drop-down box, and specify paper, colour space and if necessary profile in the printer's dialog. As Lr5user-pt says, colour management in LR or the printer driver but not both.
Setting paper type in the driver interface determines how the ink is put on the paper (drop size and quantity) which needs to be appropriate for the paper being used.