I'm not sure what you mean by "is the widget a workpiece?" Did you mean to ask whether the widget is a limitation?
As to your second question, direct (literal) infringment requires a single party to make, use, sell, offer for sale, or import the claimed invention. If the only party that will perform all of the method steps in your claim is the end user, then yes, the end user would be the only direct infringer.
Your last statement ("I am better off with purely apparatus claims") is an insight that applies in the context of many patent claims. Generally, patent owners do not want to be in a position where only their customers will infringe their claims. This is why, for example, you will rarely see claims drawn towards a method of using a medical device. Quite simply, the medical device manufacturer does not want to sue the doctors that use their devices (i.e., their customers). Rather, they want to sue the manufacturers of competing devices.
A good analogy to keep in mind when drafting patent claims is that you don't want to "kill the goose that lays the golden egg." And in the commercial world, the "golden goose" is the prospective purchaser(s) of the patented invention.