This isn’t going to he very comprehensive, but I wanted to post it to get the information out there.
Reagents now have Tiers, ranging from 1-5. As you build up Skill (a new stat exclusive to Professions) in your profession, you will be more likely to craft items at higher Tiers, eventually reaching a point per-recipe where you are guaranteed to craft a higher Tier.
Specializations are unlocked as you level your profession, and are upgraded using Knowledge. Knowledge is gained on a per-profession basis, by finding items that will grant it to you, or by crafting a recipe for the first time with the book icon that says “First Craft”.
Work Orders can be requested at a Work Order station. You can request to have something made using your reagents, and you can choose whether it can be done by your guild, someone publicly, or by someone specific.
If you want to fill out Work Order requests, you will need to go to your crafting profession’s work bench in Valdrakken. At the bottom of your crafting menu while at the work bench, you will have a new tab labeled “Work Orders”. This is where any public or personal requests can be completed using your skill and the requestor’s materials.
I hope this helps a bit. I’m on mobile, so I can’t make it too much more descriptive, but hopefully this helps someone.
P.S.: I died to a plant.