Has anyone ever flew through American Airlines? If so how does eating work?

Online it says "Travelers should note that while seat assignments are indeed complimentary for American Airlines passengers in select fare classes, those flying basic economy must pay extra to select their seats in advance (or they will be assigned a seat when they check in)."

When they say check in do they mean when you print your ticket at the kiosk or when your boarding the plane scanning your ticket? Because I checked in on the kiosk but it still didn't give me a seat and on my ticket it says unable to assign seat at this moment so will I have to pay for a seat?

Will my dog get in the way of my future plans? If so what do I do?

I'm 17 and I just got a standard poodle puppy. She is mine, and she will be my responsibility throughout her life, a 10+ year commitment. I got her as an emotional support animal, and she has been helping with my depression a lot! But I realized that my plans after high school are very up in the air, and non-traditional. I want to go into the music industry and I do not want to settle down. I really want to see the world, and possibly tour if I get the chance. I love her, and I love dogs, but the common understanding is that to have a dog you have to have the "American dream" lifestyle where you settle down. That is not the lifestyle I want, and I just want to ask if there's anyone who lives a non-traditional lifestyle while having a dog? How do you do it? Any touring musicians? Artists? Creatives? I want to keep her, and take very good care of her, just while also following my dreams!