Resolved questions
¿Cómo saber cuando usar "look for" o "seek"? / When must I use "look for" or "seek"?

American English speakers almost never use the word "seek." It sounds vaguely biblical to us. "Seek ye first the kingdom of God...". You can probably forget about the word "seek." "Look for" is very common. "I'm looking for Pete. Have you seen him?"/ "I'm looking for my keys." /"What are you looking for?"
If something or someone is "officially" lost, especially if it has been missing for awhile, then you "search" for it. "We have been searching for my dog. He disappeared two days ago."/ They formed a "search party" to search for the boy who disappeared last week."/ I've been searching for my keys for two hours.