GAFA, I am a Skywest pilot and we have had no say in the Virgin ATR project, it was just foistered upon us from above.
Due to the way our industrial agreement is written our senior mangement had no choice but to put the ATR pilots on the seniority list, all ATR positions were advertised internally however few guys took up the offer as most of us want to be domiciled in Perth (thats why we joined Skywest) and all new pilots have gone to the bottom of the seniority list based on date of employment.
We as a pilot body had no say in the "EOI" that you mention, in fact its the first that I have heard of it. I doubt the majority of SWA guys currently in the company would have had any problem with it as it does not affect them in any way, those who want to work for Virgin have left and gone already, the rest of us are happy were we are (well as happy as a pilot can be!)
As to how the cadetship would work I dont know as none of the line pilots have been involved or had any input.