BP newbie, still preping for my first.

[BassZ1890]

I have been lurking on the forums for a while and finally made an account, hoping I could get some help. So I am working on Preparations for my first Ball Python and am trying to get everything as perfect as I can. I got the Zilla Delux snake kit/tanks which has...
+A 30x12x12 tank with clamping screen top and a place for a pad lock.
+A Water bowl(I want to get a bigger, heavier one.)
+1 hide(going to get a second one)
+Zilla Bark Blend(says fir bark)(Currently in the freezer for over night because I want to make sure the chances of mite in the substrate is as low as possible. This will be a temporary substrate as I plan on switching to aspen in time)
+Zilla Tropical Mist Humidifying Spray? (anyone know if this stuff is really all that safe?)
+I super cheap looking Thermometer/humidity gauge which I plan to replace.
+2 Lamps which I plan to replace with a UTH heat pad... (Seems to be a big theme here with me XD The tank was a steal though, 50% off so it was cheaper than the plain tank they sold.)

With that out of the way, I come here to ask for the wisdom of you guru BP owners out there. There are several questions I have and I want to make sure my set up is well... well set up XD

Question 1: First of all, Like I mentioned, I plan to use the substrate it came with for a little while. Will Switching from one type of substrate to another cause much stress or irritation in a BP?

Question 2: I mentioned that my Thermometer is junk and want to get a better one. I have seen several posts saying that the Acu-Rite is a great thermometer and readily found at Walmart. I did not find any at my Walmart :S I also found a post giving an Amazon link but the main picture did not match that pictured I have seen on these forums thought the sub pictures for the product did. My biggest concern is if I DO have to order it off the internet, I do not want to get the wrong product.

Question 3: I have seen those thermometer gun things(?) that you point and press a button to see the temperature. How accurate are those and can you get an accurate reading from outside the glass tank?

Question 4: About where should thermometer probes, if using a probe based thermometer, be placed if the tank is using a UTH? I assume that ideally you want one for both the warm and cool side of the tank? Do the thermometers have two probes or switchable probes?

Question 5: Should I plan on needing a bigger tank in the future or will 30x12x12 be big enough for an adult?

Question 6: The BP I will be purchasing is, according to what I was told by the employe, about 6 weeks old. I have been going to the store and checking regularly on the BPs during the day and evenings to see how active they are. I have read that an actively exploring snake shows good health? This true or not? There are four Ball Pythons in the cage and out of the several times I have come to check only one of them has been active. The rest all lay pretty much in the same spot every day and don't really move.

Question 7: What is the best way to keep humidity up? A spray bottle of water on fine mist? Also, does the mist bother a snake?

Any other tips you can give would be greatly appreciated. I want to make sure that my snake will have a good home to come home to. This is my first real pet and I want to make sure its as happy, healthy, and comfortable as I can possibly make it. Thanks in advance for any help you can give.