Thermoelectric testing 

1) Yes. The 40 A spec on the power supply is the maximum current that it can put out. Electric devices will only draw the current they need (6 A for the peltier module you stated). However, something on the module spec doesn't seems right. Power (W) = voltage (V) x current (I). If the current is correct, then the power would be 72 W. 2) It depends what you want to accomplish. The 40 A power supply won't have a problem with it (5 devices x 6 amps per device = 30 amps needed).