Giving a list of quests (and which have been completed) without pointing to where you complete them?
I want to do most the quests but dont want to have to go to like wowhead and manually track all that.
The quest completion LUA command was added in TBC. I don’t know if it’ll be in Classic because of the modern client, but if it is, you can bet the concept will be added.
Whats that?
The command that Addons use to find out which quests you’ve completed and which you haven’t.
For private servers, a lot of people use Questie, pfUI and similar but that in no way confirms that it will work in Classic. I preferred Questie personally. Most will show you where the quest givers are, and track which quests have been completed, it also shows where the target mobs are, and a few other things most of which can be toggled off or on. I used Questie to show quest givers only, but I was still required to read the text to find the mobs. It really helped when I tried out Horde for the first time ever, and I had no clue where the quest givers were.
I dont remember Questie but I do remember using an ingame hud called Zygors. It was very fancy and told you what quests to do step by step.
Today there will be many more choices. Keep an eye out for new addons on places such as WowInterface. com and Curseforge .com
If you are willing to purchase help “Dugi Guides” ( he a wonderful person and has been around forever) will certainly have a modern leveling guide with a UI. My family used that one over the years and he has Classic plans in the works.
Hope this helps 
I remember using Carbonite Quest during TBC and WotLK. It circled quest areas and listed quest objectives, although all these could be toggled on/off if I recall. Don’t know if the addon existed in Vanilla, but it was one of the best quest helpers back then.