What are they like? - if I ask that question about a person I want to know about their character or/and appearance (are they friendly, intelligent, good looking). "For" in this instance would come at the end, but it would work better by omitting it. "How long have you been here?" is more commonly used. Not sure what you mean in the last question. If you are going to wait, then "I will stay here for an hour" or "I will stay here until 5pm". If you have been waiting then "I have been here for an hour" or "I have been here since 3pm"

1. "What are they like?" is a question about the qualities of more than one thing. Example: A: "I brought several fruits from Thailand. Do you want to try them?" B" "What are they like?" (I want to know what they taste like -- are they good, sweet, chewy, crunchy -- what are their characteristics? It's very different from "What do they like?" which is a question about what kinds of things a group of people like. 2. If you say "For how long have you been here?" it sounds outdated. Technically it's OK, but people don't talk that way today. "How long have you been here for?" is fine. Probably the best would be to simply drop both and say "How long have you been here?"