#1
Should the water be hot or cold or does it matter inside the humidifier? I have a Kyser Lifeguard humidifier. This is the first acoustic I've owned (though I've had an electric for 4 years).
#2
I don't have humidifiers in either of my acoustics and I've never heard of anyone else having one either.
Main Gear:

ESP Eclipse CTM I
Dean 'Shards' Razorback
Chapman Guitars ML-1
Ibanez AEL40SE Acoustic
Blackstar HT-5 Mini Stack
EHX Metal Muff
EHX Small Clone
#3
Quote by Birchall17
I don't have humidifiers in either of my acoustics and I've never heard of anyone else having one either.

Really? Alot of the guitar sites say thats the thing to do. How much were they?
#4
You should have humidifiers in solid wood guitars if the humidity is below 40%, laminate guitars are fine without them. As for the water, just room temperature, just distilled water from an unchilled bottle is fine. Can't imagine cold or warm would hurt it at all, but i wouldn't go out of my way to make it a certain temperature.
#5
The water should be room temperature ideally and you should be using distilled water.