The chainsmokers are a pretty good group
Yeah they had a breakout single called "#Selfie" which was a top twenty song in many counties.
They have a song on the modded version of beat saber which is a ton of fun. 
Definitely! Also their song "Don't Let Me Down" won them the Grammy Award for Best Dance Recording.
Do you know where they are from?  Are they US based?
Yes, they are an American duo consisting of Alex Pall and Andrew Taggart.
Have you ever seen them in concert?
I haven't but I should given all the American Music Awards and iHeartRadio Music Awards they have won!