Re 1. Please note that clarity is quite subjective, therefore some examiners would object to the clarity of a claimed whereas some others would not. You may find some guidelines about clarity here and there, or manuals handed to examiners, but beyond subject-matter that is objectively unclear, pretty much you cannot say for sure whether the examiner assigned to your case will find the claims clear or not.
That said, the only feature that I see as being potentially unclear is "kicking the widget to make it submissive;", because unlike the very last feature you are not referring to the made square widget or the petted widget. Perhaps you do not want to refer to "the petted widget" because you would be limiting the claimed scope by implicitly defining the order of the steps; it is fair not do so. You may add and "and", i.e. "petting the widget to make it square; and kicking the widget to make it submissive;". For me, that would be clear. It also helps if you indent each feature based on the relevant comprising.
The way you drafted those steps, the hardening step is an independent step because you are clearly referring to thr made square widget, thus it cannot be part of the making square widget step.
Re 2. You should not use double semicolon. Use "and" before the last feature of each comprising. You would also include "and" after "submissive;" because then you claim the last feature of the first comprising.
Re 3. Sometimes I have used a step by structure without receiving any clarity objections in the US, e.g. making square widget at least by both petting the widget to make it square, and kicking the widget to make it submissive.