Learn Russian: Я не хочу водить автобус.

Because it follows the modal verb хочу (I want). Just like in English (I want to drive), when you have two verbs together expressing a desire or ability, the second verb stays in its infinitive (dictionary) form.

Is хочу a regular verb?

The dictionary form is хотеть (to want), and it is a bit irregular. For я (I), it changes to хочу. It is best to memorize these forms individually as you learn them, starting with я хочу (I want).

Why doesn't the word автобус change its ending here? Isn't it the object of the sentence?

Great observation! It is the direct object (the thing being driven), which means it takes the Accusative case. However, for masculine inanimate nouns (things, not people or animals) like автобус, the Accusative form looks exactly the same as the basic dictionary form.

Where do we put не (not) when there are two verbs?

The negative word не goes directly before the verb that is being negated. Here, you are saying that you do not want something, so it goes right in front of the conjugated verb: не хочу (do not want).