To fully understand the interplay, consider terrain. This includes the placement of hills and valleys, trees, buildings, and more. When hooking up the old terrain data files to the new modern game system we realized that the way the system looked at the shape of data was different. This resulted in the updated system and classic data not aligning, resulting in weird issues like Kolkar campfires underwater or burnt-out trees from the Cataclysm era appearing in the original world.
Step-by-step class guides are on the way!  The 1-12 Mulgore Guide is the first guide to get all the individual class steps.  At the top of the guide, simply select which class you are playing and the page will dynamically update all the steps in the guide for that class (both text and images).  The rest of the guides will be slowly updated overtime to include all the class steps, but you can see how it's going to work with the 1-12 Mulgore.  I want to thank crazyK and his Placeholderguild for helping me out with the individual class content.  They are allowing me to get the 1-60 Alliance guide done while also getting all the class steps done at the same time, so everything can be ready for Classic launch (hopefully).
Swim Speed Potions (used especially at lvl 37 for Faldir's Cove in Arathi Highlands and lvl 57 in WPL).  Try to get multiple stacks of these.  I also recommend keeping a stack of these always in your bags.  You will frequently pass rivers and lakes and can use these potions to pass them faster through out the guide.  Please note that these potions do not stack with Druid's Aquatic Form and Glyph of Aquatic Form.
Nov 15 Loot sharing. Fools How stupid is the community about loot sharing? You know there is master loot right? Stop being dumb guys like holy crap. You also know that if you're the guy setting up a group or joining a group you have a option not to run or you can pick player's of different armor types... If you're a cloth wearer you just don't run or set up a group with other cloth wearers. Like this is something so simple and the community can't graps anything. I feel bad for blizzard sometimes with having to deal with brain power of this community. The community: "Oh, I didn't think about that. Derp, I'm an idiot."Plewtoe23 Nov 15
While our initial effort helped us determine the experience we wanted to provide, this second prototype really defined how we’d get there. Starting from a modern architecture—with all its security and stability changes—means the team’s efforts can be focused on pursuing an authentic classic experience. Any differences in behavior between our development builds and the patch 1.12 reference can be systematically cataloged and corrected, while still operating from a foundation that’s stable and secure.

With the Classic beta now out it seems every related article somehow manages to spark the eternal war of "Vanilla was the best WoW sucks now" and "lol nostalgia goggles, Vanilla sucked, enjoy your two weeks of Classic". I have to say, even though I understand the principles behind the battle and the reasons people behave and talk this way... I actually REALLY don't get it on a deeper level.

Nov 15 The most hardcore thing you can do. In vanilla? I have a few things that could be it. Playing on a perma death PvP server and kill kel'thuzad. Without dying even once. Being able to kill a mage/rogue/warlock/pally in all BiS gear Soloing a high end dungeon boss like rivendare or dark master gandling. Leveling to 60 with no gear or weapons or pet of any kind. That is by far the most hardcore, life threatening thing you can do in vanilla wowHavell7 Nov 15