behringer v amp has mixed review, general consent is that its great value for money, but you get what you pay for, apparantly notes sustain poorly on some settings and do that awful glitchy digital thing, iv never played through one so i cant confirm this, but iv read several reviews that do
an auto-wah is an effect that mimics the rocking of a wah pedal back n forth. the speed and depth of which can be set. personally i prefer an envelope filter, or an actual wah pedal