[RTTY] RTTY below 14072, 21072

[Steve AA7V]

Greetings,
Ok, here is ur dumb question of the day.
I am guessing the signals I am hearing on or about 14072 and 21072 are PSK.
I am correct?

2nd & 3rd (dumb) questions, I rarely hear any RTTY below this noise. 
Why do RTTY contesters rarely go below this noise to operate even though the band plan says no issue?

If I call CQ below this noise, will I (1) get answers (2) be in any violation of the so-called band plans?

I am trying to make certain I am within the rules for the upcoming rtty ww and as far as I know, I can operate below 14072, 21072.

Thanks in advance
Steve aa7v