MCM CUSTOM AUDIO 50-8396 AUTOMATIC AUDIO SWITCH 2CH LINE LEVEL

What happens if both inputs have audio signals present? will it still switch to input b (the sensing input) until there is no longer a signal in b?

Can I switch to a source manually if I want? Also, will it switch between sources if audio comes from either one, regardless of default source?

Does this favor a source? Does it stay locked on a source until it is no longer producing sound? I have had issues with fighting with auto-switches.

Does it come with a power supply or is it sold separately?