It’s a good thing that the previous expansion, Legion, was the best in the game’s history because Battle for Azeroth is coasting on its success. The major class redesigns that happened then remain in effect (though some are a little worse, and some a little better), and the combination of World Quests and Mythic+ dungeons means there’s always something to do, no matter your skill level or how long you can play.
For your tank... I'm assuming you meant which race should you be, not which class, since you seem to want to be a warrior! Well, if you were Horde side I'd recommend Tauren for the health buff. But honestly, I *never* pick a race based on the racial features - only based on the flavor. If you are going Alliance side, I am quite partial to dwarf warriors myself but pick whatever seems most fun to you!
On March 23, 2018, Zygor Guides announced that they would end support for their ESO guide. Later, via answers given on the forums, they confirmed they would not add a leveling guide for Summerset. Their guide is Public Domain with Zygor's blessing for the community to create guides. So I took it upon myself to create a Summerset guide for the ESO community.
New to Patch 8.1 is a new leveling flask called the Draught of Ten Lands which increases all primary and secondary stats by 20 and experience gained by 10%. This effect lasts for one hour and persists through death, similar to other battle flasks. This item can be purchased using a new Patch 8.1 currency called 7th Legion Service Medal or Honorbound Service Medal which can be earned doing the new incursions and Warfront activities. Simple earn these medals on your main character, purchase the flasks, and send them to your other characters. The cost is 10 of the medals.
Dugi and Zygor both had their guides updated before Mist of Pandaria was released and both guides are kept updated with all the patches and changes to the game. Dugi is way faster with updates and has a lot more. Zygor seems to hold out and then do a big update. With new content such as guides etc, Dugi is definitely leading the way with Zygor usually many months behind. Zygor now offers the same number of guides as Dugi but it took them a long time to catch up.
Even though you will invariably do a bit of soloing during your time in World of Warcraft, the game is a lot more fun when you have other people to interact with. Whether you’re starting out, or getting back into the swing of things, having helpful mentors feeding you suggestions (or gear, or gold) doesn’t hurt. The /r/wownoob subreddit is a good place to find friends to quest with, as is the main World of Warcraft subreddit (and don’t forget its helpful “Murloc Monday” thread for newbie Q&A).
You can try joining a Discord server themed around the class you’re playing, how you like to play World of Warcraft (achievement hunting, dungeon-running, player-versus-player combat, etc.), or your location, to name a few examples. World of Warcraft also has player communities built directly into the game. Find a community themed for newbies, or whatever else you want, and you’ll have a great resource to go to with questions. You might even make a few friends (or fellow adventurers).
I do not recommend going for TBC, although I remember Hellfire peninsula to be decent, everything else is rather slow. Instead go for WotLK, Borean Thundra gets you levelled very fast, and then you can head straight for Icecrown at 67, which is also insanely fast, although admittedly has a few elite quests. You can go to Sholazar Basin alternatively. 2 zones should get you 60-80 no problem.