The only difference is the subtle emphasis in the way you say it. When you say " Have you eaten ALREADY" you might stressing that someone has eaten without waiting for you. For example, "Have you eaten ALREADY? I thought you would wait until I came home!". Saying, " Have you eaten YET" suggests that you are are inviting them to eat with you. For example, "Have you eaten YET? We could grab a bite to eat together." For the second sentence, saying, "Are you ALREADY a member" sounds more conversational. Saying, "Are you a member YET" sounds like you are pressuring them to buy a membership. Hope this helps

strictly speaking, you should use "already" in case there was some action that happened before one's expected: e.g do you already have it? (I wasn't expecting him to get something very soon) have you already eaten? (I wasn't expecting him to eat something so fast) the rules says that the adverb should come before the verb/participle but I've seen that you can break the rules when you want to add emphasis on the adverb (already) but I think you should stick to the rules when it comes to take tests. and you should use "yet" in questions and in negative clauses for things that has not happened by a particular time: e.g A: Have you eaten yet? (I know he hasn't still eaten something) B: No, I haven't eaten yet "yet" ALWAYS comes at the end of the sentence/question I've also found this useful resource to complete my original idea, hope this helps you https://learnenglish.britishcouncil.org/en/english-grammar/already-still-yet-and-no-longer

hey are you speak English very well

hey are you speak English very well

As a native English speaker, these sentences hold the same meaning to me. As far as speaking, they would never be picked apart for being grammatically incorrect unless speaking to a strict English teacher.