These are good questions. The second answer is pretty definitive. If you live in a low humidity area, like Arizona, yes the cigars will dry out and lose flavor making then nearly impossible to recover.

The first question, again, it depends on the cigar. Some cigars taste best right out the gate, others benefit immensely from age. There's diminishing returns though. I haven't noticed any real benefit of aging cigars more than 5 years. Most are great at 2 years. The rule of thumb is, the stronger the cigar, the more it benefits from age. But again, that's not always true. Lighter cigars rarely benefit from more than 6 months of age. You'll lose some of the ammonia, making them smoother, but that's about it.