Always sell all items on Auction House. If you are not sure about its value, then check the market. There are some risks that item won’t be sold and you will lose money just putting it on Auction House. Good idea to make bank low level characters and keep everything there until the weekend. All sales increasing on Friday, Saturday and Sunday. Besides, you can advertise in a trade channel to inform people that an item you are selling has been put on Auction House.
Instead of sharding the zones, their plan is to shard the entire continent at launch. In Classic WoW, there are no dynamic spawns and questing in starting zones would quickly become annoying, so it's understandable that the game is all but fun when there are no mobs to kill, but layering will also cause you to see new players, every time you sign in to the game, which is a clear downside of the tech.
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.
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.