Type of outlet/cord I need to listen to audio from laptop to iPhone 7 plus?

So as you may know, the iPhone7 and onward, have the lightning cable, which has a different mouth to it as well. I'm looking for something (a cord/adapter) in which I can use my iPhone ear buds and plug it into my laptop (which uses headphone jack outlet/mouth).

Please give me your recommendations!

What should I know before I purchase a used Iphone?

My iphone 5 finally quit on me and i'm searching for a used iphone of a later model. My carrier is at&t and i'm thinking of getting some version of a 6 or maybe even a 7. What requirements are needed for a used iPhone in order for me to simply transfer my sim card? If its even that simple, that is.

Issue using headphones with iPhone 7?

I use beats ep headphones with my phone, and lately they've started acting up whenever I try to listen to music or any audio on my phone. Whenever I try to listen to music, it will pause and play on its own, skip tracks, and scan through songs on its own. I'd really like to know a way i can fix his, because it's extremely annoying.
Is it a problem with the headphones themelves, or just the adapter i'm using with my phone? Should i get them looked at by a professional, or can it easily be fixed myself?