A triangular head is a poor indicator of a venomous snake. Many nonvenomous snakes can flatten their heads into a somewhat triangular shape.
The danger of copperheads is greatly overstated. Yes, they are venomous and will bite, but they are very rarely fatal to humans.
True. A copperhead bite definitely requires a hospital visit, but as pit vipers go a copperhead bite is generally on the less dangerous side.
I wish that I could remember where I read this, but I recall that a majority of venemous snake bites in the U.S. were on the hand or lower arm, and/or involved alcohol. The implication was that a lot of the time people try to handle the things, especially while drunk.