受け身形, 使役形, and 使役受け身形. These forms confuse me to no end. Therefore, I have done a sort of comparison practice using these forms side by side. Each sentence is followed by my translation, and then a usage note underneath.
受け身：
僕は変なオッサンにわけのわからない問題を聞かれちゃった。
I got asked some weird question by a strange オッサン.
Here the adversarial/undesirable passive is used. I often confuse the undesirable passive with the causative or the causative-passive, because I think in some cases they have similar meanings, if not identical. This is why I include this usage in this practice.
*Related topic for other beginners: Subject and object of a passive sentence are interchangeable?
受け身＋てくれる：
僕は変なオッサンにわけのわからない問題を聞かれてくれちゃった。
I got asked some weird question by a strange オッサン.
Adding てくらる/てもらう/てあげる makes the sentence even harder to understand, because the subject and the action are further removed from each other. In this sentence, my understanding is that てもらう is not suitable, because it has the nuance of receiving the action after you have requested it. Although てくれる and てもらう can be confusing when the topic/subject is dropped, てあげる has a very specific direction instead. With てあげる, the action is done by the speaker for someone else, thus making it unsuitable for this sentence. I'm not sure if using てくれる is natural though.
*Related discussion & article:
a. てくれる vs てもらう when the topic or subject is implied
b. てくれる and てもらう
使役1 (transitive verb)：
変なオッサンは僕にわけのわからない問題を答えさしちゃった。
A strange old man made me answer some weird question.
*Alternative causative form: 答えさせる⇒答えさす
Tae Kim lists this alternative form as a valid causative form alternative for る verbs, but not all websites do.
Another interesting point about this -す causative form is that "it is not productive, and can only mean make-causative." (Source topic: Confusion between causatives and intransitive-transitive)
Edit: Too deep a topic and too wide a scope. I think a beginner should stay away from the alternative causative form, -す. See this article: Imabi
使役2 (intransitive verb)：
つい最近まで、なんか変なオッサンは僕を困らせていちゃった。
A strange オッサン had been bothering me until quite recently.
With intransitive verbs, usually に means the action is allowed for the performer, whereas を means the performer is made to do such action. However, note that having two を in a clause is ungrammatical, so に is the only option in spite of context. I think ていて+しまう may be unnatural.
Article about the "に/を + intransitive verb" phenomenon: With Intransitive Verbs
使役受け身：
僕は変なオッサンにわけのわからない問題を答えさせられちゃった。
I was forced to answer some weird question by a strange オッサン.
This meaning seems to overlap with the 1st 使役 usage. I think sometimes even the undesirable 受け身 expresses the same meaning as well.
Edit:
オッサン is a word that I don't really know how to translate into English. Personally, I think it is a term of endearment (up a notch with おっちゃん), but it could well be offensive if used under the wrong circumstances. 変なオッサン・変なおじさん though, is probably only derogatory.
If not too much trouble, please point out any misunderstanding and/or error. Moreover, if this topic counts as proofreading, please point it out, and then I will remove it immediately.
