I casually played WoW, but I can answer some of these. I'm on mobile so I won't be making charts for the comparison chart.

GW2 is fundamentally EXTREMELY different than WoW. Its really tough to go into GW2 comparing it to things you find there.

Valor Points- No comparison. The endgame gear (ascended/legendary) just require a lot of money and a lot of time. Plus the best gear in the game is only 5-10% better than a cheap endgame set.

Heroics- Fractals. There are mini dungeons called Fractals that scale from level 1-100. There's only about a dozen unique fractals, so as you get higher, enemies get stronger, unique things happen (I.E. Dodge rolling causes you to lose boons, healing reduced, CC causes cooldowns to be high)

Tier sets- no comparison. Endgame gear has very little damage difference compared to what you're used to.

Potion- you have a healing skill on every class.

Darkmoon- There are a few mini games you can play throughout the game similar to dark moon. But SAB is an event that happens once a year (or less)

Crafting- For legendary/ascended gear you need it, but you can feasibly skip it completely. DONT LEVEL CRAFTING ON YOUR FIRST CHARACTER. You LOSE money on crafting with the exception of a few time gated materials, getting to that point costs a lot of money.

Respecs- GW2 Specialization =/= WOW specialization. GW2's are more flavor changes. Elite specialization are a closer comparison, but a LOT less drastically different.

For example, an Ele vs. Enh shaman are different in like, every way possible. An Elementalist and a Tempest are pretty damn similar. The elite specialization gets one new weapon, a new specialization line, and different class mechanics, but the rest is the same.

Story mode dungeons contain relevant lore, and are generally easier than explorable paths.

Once you hit max level, you begin leveling your masteries. Things like gliding, legendary crafting, movement in cities, and lots of things relevant to the jungle (expansion content). So the yellow "level" numbers are really max level characters and the number is their mastery level.

You cannot directly summon people, although with waypoints it doesn't really matter. You can teleport to someone in your party with a cash shop item which is situationally useful. Or you can join them if they're in another instance of the same map which is super useful.

Must buy gem items? Not particularly. I would recommend more bank tabs, and permanent mining/logging/harvesting items are super useful. Copper fed salvage-o-matic replaces salvage kits which is nice.