I just got off the phone with a recruiter and wanted to double check the nature of my earlier assumptions, and make sure I didn't give any false information. It is true that the RC tries to give you your first choice (so there is some order value) but lets say for example, recruit A is applying for infantry, combat eng and crewman. Recruit B is applying for Combat eng, crewman and ACIS Tech.
If recruit A's main choice (infanteer) is not processing applications at the time when combat eng is processing than both applicants would be held in the same regard and recruit B would not hold any priority derived from having combat eng as his/her 1st choice trade. So at the same time yes trade choices do hold bearing for the individual in terms of, the RC will try to give you your first choice trade, but when it comes to what trades are actually processing applications the order will not matter when comparing who is more suitable for the trade regardless of what order you chose your trades.
Just wanted to get my facts straightened out sorry for any miss communication, I stand corrected in some regards due to the fault of my own interpretation but the main point is the order wont effect your status for any trades in terms of priority with the RC.
Now if all 3 of both recruit A and B's trades were open and processing I'm not sure what would happen in terms of ordered priority, but I'm sure it would be a simple answer along the lines of the RC would try to process you for your first choice trade but if something were to happen such as not scoring high enough on your CFAT or the trade closing during processing the same rules would apply, i.e that the order in which you chose the trades would hold no bearing and you would be processed for your second choice without penalty providing you still meet the standard for that trade. Again I don't know for sure that is just what I imagine would happen if someone knows better than please correct my ignorance.
Regards and sorry if I am just repeating what you posted Hatchet Man and Deelo and just rewording it, I just want to make sure I am clear on the subject and anyone else who reads into the merit list will get their questions answered through the search function.