Shamas
You can order what ever frequency you prefer or buy what the LHS has on the shelf. To get the frequency you want usually just add the number on the end of the radio part number when you order a radio.

I am not sure about the blocked frequencies you listed but at our field channel 20 is banned because of harmonics caused by TV channel 4 audio carrier. We also have a frequency agreement with a fellow that flies close by but dosen't want to join the club. We ban channels 41 thru 49 at our field for him to fly at his house.

Hope this sheds a little light on your questions
DEG