Well,for all the palos you have a phrasing of 12 beats as you said.You have mainly 3 forms of accentuation according to the palos:
-accents on the 3,6,8,10,12 beats
-accents on the 1,3,5,8,11 beats
-accents on the 1,4,7,9,11 beats
It's particular for tango.In most of cases when you play tango you don't begin on the first beat"contre-temps".You have an accent on the 2,between the 3 and 4, on the 5
I don't know if you have ever performed tangos but the accents are alaways mentioned on the music.
Check Astor Piazzola tango's"la muerte del angel" or "verano porteno",very cool stuff to play...
Tocaores don't play at all tangos.Tango wasn't a music imagined to guitar but more for the bandoneon to go with the dancers.It belongs to latin america culture like other palos(rumba...).The main tangos or milonga I played are Piazzola and Cardosso ones and not from tocaores...

Sorry for my english,it's difficult to explain in an other tongue than my mother one...

Saludos

El tocaor.