You have some nice examples and a good eye, just consider that when you’re shooting a car, you want it to be the centerpiece. Nothing should be in the way or steer a viewer’s eye to something else. For instance the photo of the car coming out of the garage with lettering on the left, it’s distracting, crop the photo to make the car the focus. The lamborghini framed by leaves, right idea but it’s zoomed in too much. The leaves are blocking the driver’s door. Take out some books to understand the law of thirds.

That’s for you to decide and suggest, you’re the one with the idea einstein ;D. I don’t know what the reference is to them smiling when it sounds like you’re taking photos of their tattoos. What if someone has a full back/arm sleeve, etc?

Just be upfront, flexible, but also have some idea of what you’re planning to do. “Ok, I’d like to take photos of each of you in x position, perspective, and here’s how much time I’d like to spend”. You don’t want to overcommit to anything and I’ll find the right balance with the staff. Believe me, anytime someone gets a chance to get free photos, they may be asking if you can do this again - totally up to you, also good way to get traction on a small side hustle.