1. When producing goods, can you daisy-chain production? For example, can you turn a hemp into a canvas and then use that canvas to produce a tent all in the same turn? Or would you have to have the canvas already in hand at the start of the production action?
We've played that you can daisy-chain, based on a strict reading of the rules. Manufactured goods are taken into the player's hand as they are produced (page 6), and the rules don't specify that good cards are in hand at the beginning of the production action -- only that they are in hand.
2. In the guild variant, if you use somebody else's building to produce a good, does that use up that building's production quota for the rest of the round? Or can each player produce a good at that building each round? (We didn't use the guild variant yesterday, but we plan to use it in our next game.)
We haven't tried that variant, and I don't see any clue in the rules for how to answer your question. But I'd hope that if each building can be used only once per round, then the business owner would have the right to refuse.