Doomguard: The Doomguard serve as the Burning Legion’s lieutenants, captains, and generals. While it is incredibly unlikely that a demon hunter would be capable of defeating a Doomguard within their summoning circle, those that succeed would be granted overwhelming and overbearing power, the like that few would be able to contain. However, just as the Doomguard serve as the Burning Legion’s battlefield leadership, perhaps a sliver of that might be imbued within the handful of demon hunters capable of binding themselves with one and surviving.
When hovering over an ability, the tooltip will tell you whether or not that attack is weak or strong against certain pet types. Additionally, you can hover over the opposing team's pets and view their attacks during combat. This will be important since it’s a good idea to pit a pet that's strong against the opponent's pet who's vulnerable to that type.
No he's just not paying attention. The wanted quests are built into both the leveling guides and the "Zandalar Forever" achievement guide. They aren't in the rep guide because they are not repeatable and by the time you hit max level they should be done. You'll also notice the rep guide doesn't contain every single possible completable quest that rewards rep. It is designed to focus on repeatable objectives, world quests, large quest lines, and missions.
Things like Tauren melee reach being bigger, which is something I experienced going away live during Black Temple Illidan progression (at least for that particular encounter), is confusing to players as it's a significant advantage over other races in some instances. No quest tracking is another apparently confusing issue, as many Mankirk's WIfe seekers well know, and there's a whole lot more where that came from:
Swim Speed Potions (used especially at lvl 37 for Faldir's Cove in Arathi Highlands and lvl 57 in WPL). Try to get multiple stacks of these. I also recommend keeping a stack of these always in your bags. You will frequently pass rivers and lakes and can use these potions to pass them faster through out the guide. Please note that these potions do not stack with Druid's Aquatic Form and Glyph of Aquatic Form.
However, after a while the novelty of it wears off and you do start getting a little bored of all the eating and drinking (and wondering why your character isn't getting to Kul Tiran levels of fat), especially if you hop on to BfA for a bit in between. The difference is huge and once you're used to just slamming into 5 mobs and downing them quickly it can get a bit boring to just pull 1 mob at a time and then wait and wait. The really low levels aren't that different between live and Classic in terms of gameplay however, as the small amount of abilities means combat isn't exactly the most exciting thing in either. On live you get past that pretty quickly, but it takes a while longer in Classic (especially if you're playing solo).
Each battle that you win will yield experience for each pet that participated. However, deceased companions will not receive any experience (so make an effort to keep them alive by swaping in a different pet). Experience gains are based on your pet's level compared to the wild pet. Defeating a higher level opponent will grant more experience than a much lower level one, but be ready for a tough fight!