It all depends on what type of wood the holder is...... if it is made of cedar, then YES, I would keep it in the humidor if you have the room. If it is some other type of wood then I would not keep it in your humidor. The wood might soak up too muck of the humididty in your humidor.

As for wetting your finger and wiping the inside, that is something I have never heard of. But, if the cigars are inside of cello then I wouldn't really worry. I wouldn't use the wooden travel holder for more than two days...... unless they are wrapped in cello, then you can probably get away with a little more.

As for keeping them in the tubes...... my rule that I follow is..... if it comes in cello, it stays in cello. If it comes in a tube, it stays in a tube.