answers:

Chlorine bleach will kill mould but it is also toxic to people in LARGE amounts – it is in our drinking water but remember the Union Carbide accident in India. Breathing mould spores, on the other hand can lead to a lot of other health problems such as asthma. For myself I would see a DROP or 2 after a good cleaning as the lesser of 2 evils. Using distilled water would be very expensive however it does have the advantage of not containing any minerals which create a sort of lime-scale dust. Mains water is essentially sterile as is boiled water so that is not really the issue but I do find it hard to believe that you live in Britain and want the air to be damper.

answers:

The ideal humidity in a humidor is around 65-75%. The more empty space, the more readily the humidity will drop. This level of humidity supports an even burning of the cigar. At a relative humidity level of 70%, and a temperature of 64°F the air contains approximately 10 grams of water per cubic meter of air. In such an environment, the cigar should absorb the ideal rate of humidity of 14% of its weight.
Just as important is the temperature inside the humidor A temperature of 65-75F is considered ideal. At lower temperatures, below 54F the desired aging process of the cigars is impaired. Therefore, cold wine cellars are only suitable for cigar storage to a limited extent. Even worse are high temperatures. When a constant temperature of 80 degrees F is maintained, you can invite worm infestation and cigar rotting. For this reason, the humidor should not be exposed to direct sun light.

The most often used material is the inexpensive green foam found in the bottom of flower arrangements at the florist. This is extremely effective because of it’s superior ability to retain moisture.When first using your cigar humidifier, I recommend you thoroughly moisten it with a propylene glycol solution, often referred to as humidification solution. This is made up of 50% propylene glycol and 50% distilled water.
Let the solution be thoroughly absorbed before turning it over and gently shaking out any excess. Wipe dry and place in humidor.
The humidification solution will help prevent growth of bacteria and allow you to better regulate the environment.
Do not use this solution more than once every 3-6 months. A good rule of thumb is to use it only when you have a dramatic change in seasonal temperatures.
Excess use will result in a diminished capacity of your humidifier to properly maintain its environment.
Normal maintenance of your cigar humidor is done by adding only distilled water. Regular water has too many minerals and will choke your humidifier, eventually making it useless.

I personally use the Diamond Crown and Oasis humidifiers.
Higher quality but well worth it if you have any money wrapped up in your sticks.
PS: DONT trust an analog hygrometer (often considered by most as for an asthetic appearance to their humidors – Digital is more accurate and monitors temp and humidity)

answers:

Can’t seem to find any ‘how-to’ site or download
for making your own ultrasonic humidifier.

All I could find were sites that recommend
various brands and types.
Everything from room humidifiers to whole house
and furnace humidifiers.
None of them seem extremely expensive.

Regardless of which brand you choose or if you
are able to make your own unit, remember,
ultrasonic humidifier instructions recommend using distilled water rather than tap water. In this case, it’s not a come-on to get you buy water.
Here is a link that explains why :

http://www.associatedcontent.com/article/419686/health_concerns_related_to_using_tap.html?cat=5

Scroll down at this site for the best tips for keeping
your humidifier clean as this is very important :

http://www.mayoclinic.com/health/humidifiers/HQ00076

Sorry I wasn’t of more help.
Hope you find your answer.