Questions & Answers about Ta długa podróż była za męcząca.
Could I use zbyt instead of za in this sentence?
Yes, absolutely. Both za and zbyt mean "too" when expressing excess. You could say zbyt męcząca and the meaning would be exactly the same. Za is just a little more common in everyday spoken Polish, while zbyt sounds slightly more formal.
Why is everything feminine (ta, długa, była, męcząca) when podróż ends in a consonant?
While most Polish nouns ending in a consonant are masculine, podróż (journey) is one of a few common exceptions. It is actually a feminine noun! Because of this, every describing word and the past tense verb must match it by taking feminine endings.
Since była (was) is a form of the verb "to be", shouldn't the adjective męcząca be in the instrumental case?
No, because męcząca is just an adjective describing the subject. In Polish, when you use the verb być (to be) to link a subject with an adjective alone, you keep the adjective in the basic nominative case. You only use the instrumental case after być when you are linking the subject to a noun or a noun phrase.
I recognize the root of męcząca. Is it related to a verb?