Q1：

It basically means that the gradle zip file in the cache folder is corrupted, if you don‘t want to change the version like the up-voted answer 
then you must delete the folder for your gradle version you‘re using for this project from the below path.

Then just retry the sync and android studio will download it again

C:\Users\ [user here]  \.gradle\wrapper\dists
ex: if you‘re using 3.3 for this project you‘d be deleting the folder

C:\Users\[user here]\.gradle\wrapper\dists\gradle-3.3-all