#3
1)
eh, a delay pedal for $30 is good enough to have some fun with (though that may be just me, as if I could I'd make up my entire pedalboard out of a dozen delay pedals)

2)
M = mono
S = stereo (no idea if it does wet+dry or ping pong delay when in this mode)
#4
Lol theres nothing wrong with behringer pedals I use thier delay, chorus and boost, just whack em in the fx loop n ur away..

For playing live and at home their nothing wrong with them.. (gig'd mine a fair few times) cheap dont mean its crap!, only down side is the casing is plastic but unless ur planning to jump onto ur pedals they'll be fine! lol

chris