I am trying to figure out the same thing about my turtle. I found him at the beach (and no he's not a sea turtle) about a year and a half ago, and he is still only about 2 inches big. But anyways the only thing I have been able to find out for sure is that if it has a red stripe on its cheak then it is a red eared slider. but this website might help: http://www.turtlecare.net/what.htm
yes
It depends on what type of turtle it is
Sea Turtle
Sorry, but you need to describe your turtle.
4 feet Actually it depends what type of turtle, how old it is, and if it is sick...
Green Sea Turtle
it depends on what type of turtle and how heavy it is
sea turtle like in water
snapping turtle is a secondary consumer
I don't know. It sometimes depends on what type of turtle it is.
a type of leatherback turtle does
Google is probably the best with endless pics of any turtle just type in pics of turtles or your specific turtle type