"We know how to eat."
A question where one has to pick the correct translation. I picked the above: nous savons comment manger. Duo. said I missed one translation: nous savons manger. That's not correct, is it? That just says: we know to eat.
I'm not positive on this, but I believe "savoir" can mean both "to know" and "to know how". For example: "Je sais nager" is "I know how to swim" or "Je sais monter une cheval" is "I know how to ride a horse"
Both of those examples would sound silly in English without the "how" but I've seen them in French so, so as far as I can tell the "comment" is optional or changes the meaning in a very subtle way.
Unfortunately not. Both "savoir" and "connaître" can translate to "to know," but they have different meanings.
"Connaître" can never refer to a verb (as it does here). It is used to talk about about being acquainted with or familiar with a person, place, or a thing. For example, to talk about knowing a person, you use "connaître," and to talk about knowing a place (not just knowing of it, but actually being acquainted with it), you use "connaître" as well.
"Savoir" is usually used to talk about knowing how to do something, as used here, or knowing a fact.
More info here: http://french.about.com/od/grammar/a/savoirconnaitre.htm