Angola is played slowly,(which is a relative measure), the tempo depends on how fast you want to play, iv heard this rhythm played very slowly and very fast, so anywhere inbetween does fine

(there are no specific rules to tempos, since music is an essential part of the Jogo de Capoeira, and should show the players in the Roda how fast they should play and how.... But it is played slower than São Bento Grande (de Regional), which also is going to be posted in due time..fast and slow are very relative in Capoeira, so one would be better of to thick of what kind of game is played, if the Berimbau plays Angola, then the players try to trick each other to make mistakes or be off guard so as to trap them. If São Bento Grande De Regional is playd it indicates a fast high kicking and lots of floreios, jumps mortals etc, and if Iuna is played then only people graduated can play, elogantly.. and so on. There are so many different rhythms and games in capoeira that i cant even begin to list half of them.
Hi laurent, the Gunga and Viola are also berimbauas like Medio, Gunga is the largest of them which controls everything happening in the Roda(lowest sound), Medio is obviusly the one in the middle, and Viola is the highest piched one which does most rhythmical improvisation. There is also a fourth berimbau which is Berra-Boi ,which sipply put is a large Gunga(and if in a Roda controls, the largest berimbau controls the Jogo).