Https doesn't encrypt the URL you are reading, which kind of gives away what content you're reading when it comes to wikipedia.
Yes it does. Your dns request for the hostname and the ip address you connect to might give away the fact that you're reading wikipedia but the actual path will be encrypted.
Unfortunately, this is of no help if Wikipedia or it's hosting provider (and therefore every machine it runs on) is compromised.
Surely it does. Did you think GETs are transferred before the encrypted connection is established?
It absolutely does encrypt the URL aside from the IP you're connecting to.