Hello Pascale,
Reading sources/waqtel/nametrac_waqtel.F subroutine, I would say EUTRO tracers first, then MICROPOL tracers if you have not added personnal tracers first with the same name as the MICROPOL ones.
Anyway, if activating MASS-BALANCE (default = NO), reading the listing of mass-balance gives you the order of tracers.
I am surprised by your last question about the name of tracer variables. I can read the expected ones. At what step have you read tracer1, 2, 3 etc?
Which release do you use?
Please write in English otherwise, everybody cannot answer you or understand you.
Hope this helps,
Chi-Tuan