A: Usually the taste of cedar imparted from a humidor is minor. Especially if you are not aging your cigars for a long period of time. If you find your cigars to have a strong 'cedar' element to them, it's probably due more so to the cigar you are smoking than the humidor.
A: This humidor's small enough that you can really mount it wherever you like. Any side, on the lift out tray, or even on the glass. Just a matter of preference, but if it was me, I'd mount it to the back wall in the center.
A: On the inside of the humidor there is a circular opening where the hygrometer is mounted. Gently press from the inside of your humidor until the hygrometer pops out of the front. To mount it back in, simply press it back into the hole.