Learn Hardcore Japanese: erebeetaa wo tukatte mo ii desu ka?

The particle を marks エレベーター as the direct object of the verb 使う. In English it corresponds to the object marker “the elevator” in “use the elevator.”

Why do we use 使って instead of the dictionary form 使う here?

We need the –て form (使って) to connect with もいいですか. The structure [verb–て] + もいいですか means “Is it okay if I do [verb]?”

What does も add in 使ってもいいですか?

The も comes from the conditional ても (“even if”). So 使ってもいいですか literally means “Even if I use it, is that okay?” Functionally, it expresses asking permission.

Why is です included in いいですか? Can we omit it?

です adds politeness. In casual speech you can drop it and say 使ってもいい？, but in most formal or business situations you include です to be polite: 使ってもいいですか。

What role does the final particle か play?

か is the question marker. In written Japanese it clearly indicates a question. In casual spoken Japanese you could omit か and rely on rising intonation, but in polite speech you normally keep か.

Why is there no subject (like “I” or “you”) in this sentence?

Japanese often omits subjects when they’re clear from context. Here the speaker is asking “May I use the elevator?” so the subject 私 is understood without being stated.

Could I use a more formal or honorific version for a superior?

Yes. You could say:
エレベーターをお使いになってもよろしいでしょうか。
This uses the honorific verb form お使いになる and the polite phrase よろしいでしょうか.

What’s the difference between 使ってもいいですか and 使ってもかまいませんか?

Both ask for permission. 使ってもかまいませんか is slightly more formal and literally means “Would you mind if I used it?” かまいません carries the nuance “It does not matter to me.”