Before we talk about layering, it's important to talk about the sharding technology used in modern-day World of Warcraft. When a zone in the game becomes overpopulated, players will be seamlessly moved onto a different shard, which is essentially another instance of the same zone. It is important to note that you will still be able to play with your friends, because you are moved to the same shard when you create a party.
This is definitely why we do a beta test. We can also do things like reset the realm at a busy time like 4:30pm PDT to try and find the source of a certain issue where a crocolisk is losing it’s brain due to how multiple processes are interacting and mirroring code to form a cohesive world. There were similar types of issues like this back in 2004 but we wanted to try and resolve this one before the weekend for the folks who are testing. (Blue Tracker / Official Forums)
Where to get materials and reagents you may ask? Buy for cheap off farmers in bulk or track Auction House lots. Get in touch with most big sellers. Communication is important here, send a whisper or write them a letter. It would be good for both of you to establish business relationships. Constant suppliers and buyers is convenient for both parties to save the time and effort.