A whole lot of your sharpening issues are taste, paper and subject matter dependent. Don’t get all uptight about sharpening until you have the printer in hand and are ready to print a few. Plan to print on letter size paper first, or plan to set up and print segments of your image onto portions of your paper to see how sharpening (or not) works. I have a Canon Pixma Pro-1, and if I only have 13x19 paper in the paper I’m using, I’ll select an important part of my image and print only that portion, but at final print size, on different places on the same sheet of paper to see what I like, before the final print. I can do this easily in Photoshop, I haven’t tried printing from PL2 or 3.
Also, if you have the Nik Collection, I would definitely examine the output sharpening options in Sharpener Pro. I’ve used that often as a last step before outputting a file for inkjet or halftone reproduction.