A popular one here is 'never end a sentence with a preposition'.. really? who says?
Exactly. Believing that to impertinently split infinitives is wrong, was based on the old idea that Latin is somehow superior to Germanic languages and that English needs to unfortunately fit itself to the principles of Latin. Just because Latin didn't, to be 'pure', English shouldn't.
Much the same in Polish - some very archaic ideas still float around. The grammar of a language is a description of how it's used, not a set of set of rules that can never evolve or be challenged.
the whole book starts with "W". As does the next sentence.
Yes, tons of such examples. Sometimes sentences start with Ów
too - uncomfortable for a learner, however perfectly possible (and in current use) in Polish.