The three black spots on the side panel you mentioned are Taylor's unique ES pickup system, the full name is Expression System, which is Taylor's patent, which means that only Taylor's piano is equipped with such a pickup. The advantage is that you can better identify the sound of the piano body, not just the sound of six strings. In addition, it can also minimize the damage of the pickup to the piano body. Taylor is widely praised on the electric box piano because of this ES pickup.
This ES pickup truck is not the new one upstairs. Since 1990s, all Taylor's electric box guitars have been equipped with this kind of pickup, which is not new. The famous ES pickup ... The difference is that some models are ES and some models are ES-T. There is no difference in appearance between them, but the pickup effect is much worse. As for what this is like, I can't judge.
About this ES pickup and Taylor brand, you can search for it yourself. There are many more detailed introductions, so I won't say much.