Yes you can use the non-finned pads. If you do mountain descents or ride in extremely hot weather (as in the Pac Northwest lately
) the fins might be a good idea. Here's Shimano's pad choice explanation.
Brake Pad Breakdown Metal versus Resin Pads: What you need to know (shimano.com)
Also, here is the Shimano Parts Fiche with part #'s you can use for a search on the net.
EV-BR-R9170-4074D.xls (shimano.com)