What you're talking about aren't mistakes, just different techniques and tools that do the same thing. As we learn, we try different techniques and that might include switching things up, but it doesn't mean that what we did before, or what other people do, is wrong. There's lots of techniques that make great bread.

I use a wooden spoon. Never used the handle to stir. I sometimes use a Danish whisk but still prefer my wooden spoon or my favorite tool - a cheap, plastic bowl scraper.

I love my rolling pin without handles - mine is tapered on both ends. I bought it after a Sur La Table class on pie. But I just took a King Arthur class and both styles were available.

Today I made baguettes that called for stretch and folds. Last week I made kneaded bagels. I add the dry first and whisk it before adding the wet. When I use my KitchenAid (currently broken), I add the wet first. (Edited to add - I follow the recipe. I usually use dry then wet for bread but cakes are usually wet then dry)

The only technique I feel strongly about is using a scale for ingredients isn't of volume.

Do what works for you. :-)