I don't think so. If you're pitch correcting some people might consider it "cheating" but otherwise I would say most everything else is delay, reverb, harmony, filtering, etc that is certainly valid for artistic expression.
There's no such thing; there never was. Where I am going you cannot follow me now.
^As above.

Anyone that is doing the frowning is typically just a snob, most likely an intermediate musician at best, and doesn't really understand what music is all about. Use whatever tools you have available to make the best music you can as determined by your own ears.

I don't know anything about vocal pedals though sorry
Effects are only wanky if you use them tastelessly or to hide mistakes. There's been plenty of times I wished the vocalist in the band had some effects to fill up the space better. Reverb, tap delay, EQ... Definitely useful for vocals.