Everything has been said

USE

Yes
Yes
Yes
not

SOUNDS

Not
no effect on connected feedback is very rapidly
odd / does not return all the sounds of the guitar when plugged into an amp
to try on a live sound system (without amplifier)
serious no problem / no acute problem / medium practically

NOTICE GLOBAL

2 months
mild, beautiful ...
the sound power is mediocre, very good for practice, the stage out of the question
moderately well
not