"As" means the actions (follow, try) will be concurrent if you obey the command in the first clause. "Who" means the subject of the second clause is a person that was already mentioned in the first clause.

"As" is an adverb that modifies the verb "follow" by answering the question "when?". The phrase "as he tries the delicacies" functions the same grammatically as the adverb "tomorrow": "Follow our favorite, Greg, tomorrow". Phrases that answer questions like "when?", "where?", or "how?" tend to be adverbs. There is a logical error in your sentences: Peru, Morocco, and Japan are countries, not delicacies.