This is something that people really need to start to understand, not just for Classic or WoW but software developement in general. Fixing a bug isn't just flipping a switch or changing a single digit. You have a machine with literally hundreds of thousands of parts, designed by dozens of different people at different times over the course of 20 and more years. You change a single thing and it might break 50 other things in very subtle ways that might not even emerge until months later (i.e. the very high M+ keys some players got at the start of BfA).
It’s important that you levelling in certain areas around your characters level to gain the full XP reward for slaying monsters. Below is a list of all the best location for grinding XP from level 1 to 60, these locations are good for AOE spells and should have plenty of mobs. The Level you should be before you enter that specific location will be indicated to left in a Blue Color for Alliance [Lvl 35-39] and Orange Color for Horde [Lvl 35-39] the Mobs you are looking for Bolded [Mob Name].
Gold in World of Warcraft Classic is an integral part of the game. In this article, we will discuss the importance/role of gold in vanilla WOW and how you can obtain it easily. Gold was vastly more important in classic; it gradually became less relevant/powerful as time went on in the current version of the game. It is very tedious (but not difficult) to gain gold in vanilla, which is why many people choose to purchase gold.
I joined twitch in 2013 with the gamer name of FuriousPaul and I streamed speedruns of the classic Castlevania games from 2013 - 2017. Lately my streams have died down quite a bit due to working on Classic WoW leveling guides every day. Although I may come on occasionally and play a random game for fun on my Twitch stream. I talk a lot about WoW speedrunning on my channel, so feel free to follow and hang out to discuss vanilla WoW if you like. Classic WoW will be my main focus for a long time. Unfortunately I will have to wait until Classic WoW comes out before I start streaming it.
Only really to expand on Gráinne's comment as regards the 'collecting' and 'roster development' sections - which are, as said 'distinct' although they are intrinsically linked - I would like to point you in the direction of the in-game Achievements > Battle Pets > Collect tab. There are a series of achievements called Raiding With Leashes, pretty much all of which can be completed via the auction house - if you have the gold/inclination - or by completing old raids.