Questions about Portuguese cavaquinho tunings and strings

[zabolekar]

1. Sometimes I see sets containing identical strings (e.g. Dragão 057 has four .009p strings) or different strings (e.g. Dragão 062 has one 0.009p, one 0.011p and two 0.012p strings). When does one need which?

2. Which strings does one need for GGBD/AAD#E and which for CGAD/DABE? Or can I always retune a cavaquinho from one to the other without changing strings?

3. What are the advantages and disadvantages of GGBD and CGAD? (I've ony tried GGBD so far)

Thanks in advance.