Not easy questions to answer simply, except the last.

Camcorder mics are usually poor and can suffer from picking up camcorder motor noise. Any decent (50+ quid) mic will be better.

As for the other stuff, well depends on a gadzillion factors really and I am certainly no sound expert and no wedding vidder.

Off the top of my head I would say a decent shotgun (meaning expensive ) mic from six to twelve feet away pointed accurately would do the job.

I dont know what the deal is with stands / lapel mics ect at weddings, I have always presumed that you just have to 'fit in'

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I have two prejudices - I am anti HDV for consumer camcorders, and I eat mooks who claim to be pro wedding vidders and ask dumb questions.

www.zaskarfilms.com You tube channel 'zaskarfilms'
JVC DV5001e (big cam), Sony PC6E (tiny cam), Vinten pro5, PAG light, SM58, Sony ECM50, Sony C-76, 0.5x convertors for sony, Rode video mic, Vegas 7.