On your AMCAS app, any “publication” entry is specifically used for citing the actual article—NOT for describing in detail what your motives were, what you contributed, etc. In this entry, you just write out the full citation of the article and the single date it was published, and the hours can be “0” if you have a separate entry describing the research experience in more depth. This separate research entry would also be the space where you say how many hours you spent.
You can allude to your publication in this general research entry, but I believe you can and should have a separate entry solely dedicated to citing that publication. So, based on the options you’ve presented, go with the first set, but modify it like this:
Experience Type: Publication
Experience Name: “__ author of (topic of article, e.g. 3D printing) publication”
Date: Pub Date
Hours: 0
Description: pub citation
And another activity as:
Experience Type: Research/Lab
Experience Name: research assistant in (insert topic, e.g. tissue engineering) lab
Date: x/2019-x/2020
Hours: 300
Description: Concise overview of what your lab did, what your projects were focused on, and maybe briefly listing some of your roles/skills.
MME: Explain why the experience was meaningful. Maybe talk about what drew you to this type of research, why you were fascinated by it or why it was important that you leveraged it to find solutions to problems you cared about. Allude to the project that produced the publication (i.e. through our collective efforts, we discovered ___. These results were ultimately published in (insert journal), and I’m very honored to have contributed to the advancement of cancer/AIDS/diabetes care.)