Is the Guide the ultimate crafting guru?

In the Guide's crafting help menu, you can give him an item and he will show you what you can make with that item and which crafting station you have to use to make it.

Does the Guide know all of the crafting recipes? Are there any 'hidden' recipes that you have to discover for yourself by collecting all the correct ingredients and approaching the correct crafting station?

The guide does know all of the recipes in the game, you only need to give him a component and he will show you items that it can make. source

Any material that can be used to make something, the Guide will know how to make.

You will also notice that every item that can be used to make something has the type "Material" in its description, so you know right away if something can be used to make something else. Anything without "Material" in the description is not an item you can craft with.

Silt and Slush are not materials, but can be used with the extractor to 'make' random ores and gemstones.

EDIT: Silt can be used to craft Stucco blocks in four different colors.