If I am in a relationship, I want to talk to her, every day!! Especially when we are apart, and have different schedules. A little call, email, text, just a way to know that they are doing ok, and things are good. Any lack of contact for more than a day, and I wonder if she was in an accident, or something bad happened!!
Well if he/she is away on a trip or something and unable to phone or something, then it's kind of a given, NO. But if you are able to talk to each other, you should want to talk to each other at least a little bit a day.
Every "available" day, yes. But if you're working hard, studying or are on a field trip with no internet/ bad connection then it shouldn't be an obligation. So long as you inform each other about it beforehand.
Of course! At the very least a simple "Hey, sweetie. How are you?" type of text if they don't have time for much else. (And no one is ever too busy for a quick "Hi." all day and night.) Personally, I'd want to text her whenever we both had time. (If not direct contact.)
They should talk everyday especially if they live together and have the same or close to same work schedules. If they don't it could make one of them feel like through did something wrong. Long distance relationships they should or it could make one of them feel they can't trust the other.
Yes, I think this is what separates that couple from the regular people you may talk to. I believe that your partner should be your best friend, so why wouldn't you to want talk to them everyday. Something simple as a "I love you" or "how was your day?" It doesn't have to be an hour long conversation about the dynamics of your relationship, but simple little reminders that let that "special person" in your life feels special.