When it comes to table top humidors, what qualities do you find to be most important?

I ask because I'm in the process of designing a table top unit and a few questions have arisen.

I see that most cigar gurus look for a 3/4" wall thickness to the sides to reduce air flowng through the wood sides of the humidor. Does a humidor need any air exchange?

There seem to be many positive reviews of the bead style humiliation system, does this system allow any regulation?

What sort of hygrometer is best?

Thanks for letting me pick your brains.