The CH has always the sound CH (as in church). The pronunciation with SH correspond to French, not to Spanish.
The Z has a sound S in America
Spanish and TH in Castilian Spanish.
The V and the B have the same sound B.
The pronunciations of the surnames asked are:
Chávez - CHAH-bes in South America
(the Venezuelan president is Hugo
Chávez) or CHAH-beth in Spain.
Zamora - thah-MOH-rah in Spain (it is a Spanish town name and a surname derived from) or sah-MOH-rah
The pronunciation of Madrona is correct.