To answer the first question, most built in Hygrometers are analog. I've yet seen a digital for a built-in hygrometer. If it is analog, then you don't really want to use it. Purchase a good digital hygrometer because they are more accurate. From what I've read about they built in hygrometers they are unreliable and most people don't "use" them and have a digital inside the humidor they trust.

However, if you want to use the hygrometer that comes with the humidor, then it should come with a set of instructions for setting it up. Follow them and hope it's accurate.

I know this don’t answer your question, and maybe someone with more experience with a built-in hygrometer can help.