i've got a few questions i've asked before, but couldn't get a solid answer (or one i was looking for)

i live in arizona, were it is hardly ever humid, (only during our monsoon seasons) this is bad for the guitar, correct? i've made myself a humidifier, poked holes in a ziploc bag + sponge and put it in my case. my question is, will general playing effect my acoustic? i play for about 3-4 hours a day (electric) and i can only assume i'll devote more time to my acoustic. it's pretty cold in my house (usually 25+ degrees above what it is outside, which never gets below 40) and i need to know all precautions i must take, money is tight and i don't have the cash to fix it if something bad happens!
My gear
Ibanez RG7321
Jackson Warrior WRXT *FS/FT*
Jasmine J35
Squier Fender P-Bass
Ibanez TBX150H
Crate 4x12
Fender Rumble 60

Go get a 25$ humidifier and all should be fine. Here we leave for 1 or 2 weeks at a time where the house drops to about freezing. Everynight it drops down low when our fire go's out. Even on my higher tension guitar (12 string) it has shown no warping from temperatures so you probably will be just fine.
Do you use a BR-600?
If so, click here to join the group thats made for you!
If you can't afford to take care of it now, you surely can't take care of it when it goes bad....

I had to help move a friend from Arizona, and was surprised at how the wooden furniture just fell apart. Some of it we just put in the garbage.

The constant air conditioning dried everything out.

I saw two different humidifiers that I put on my Christmas list:



I don't know which one I'll get, cause we aren't opening presents until this weekend.