The plural for bus is buses. The confusion between buses and busses likely comes from situations where English words double their final consonant. English nouns don’t do this. It happens most often for English verbs. Busses was once acceptable as a plural for bus, but it has since fallen out of use.
How do you compare one thing to another in English? What if you want to explain how something is better than all the rest? In English, this is pretty easy to do. We call a word which compares the properties of two things “the comparative”. If we want to talk about how something is the best of all, we call that “the superlative”.