Question 1

can the macbook still be updated to macOS High Sierra?

Accepted Answer

Yes this is a 2015 Model. It can be upgraded to the latest iteration of OSX (Mojave)

Question 2

Does this come with an Apple-brand (or another type) charger?

Accepted Answer

Mine came with an Apple-brand.

Question 3

How many cycles on the battery?

Accepted Answer

I'm not sure what you mean by cycle on the battery and I've only had the computer for a little over a week now. But what I have been doing is just keeping it plugged in. I was on a trip shortly after receiving the MacBook Air and kept it plugged in mostly while I was away. Then coming home I had it unplugged for 13 hours after a full charge and it was in sleep mode the entire time. When I got home it was still at 100%. Surprised me that it had not lost any of it's charge.
I don't know what is supposed to happen, but my older MacBook Pro would have lost at least part of it's charge.

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