Yes, I mostly use wireless earbuds but you never know when you have to use a wired earbuds like if you forget your case and your earbuds are out of charge.
I'd say the only thing more rare than forgetting your case and your buds being out of charge...is remembering to have a spare set of wired headphones in your pocket for just that scenario.
All three options. I have a nice set of USB headphones for my computer. It would be really nice to have support for those included. There is plenty of space along the side of the phone to fit an extra USB-A port.