You got that right about the brokerage fees from UPS and FedEx.
There are no duties on 99% of purchases since NAFTA kicked in. I buy lots of items in Michigan and never pay duty. I even bought my tractor in Michigan and only paid provincial and federal sales taxes when I brought it over to Canada.
Correct. Anything made in the U.S. (and Mexico??) --even partially-- would not be subject to duties. However, as you know, most things nowadays are made elsewhere, so duties still apply on a lot of different products.