It generally means you are facinated or infatuated with them.
I have one friend that I can talk to for hours at a time on the phone. we've known each other for 10 years. I like to think we have a good connection. The rest of my friends, we text for hours or hang out and talk for hours. I don't like talking on the phone that much, but with him it's ok
Probably, it all depends on the broadband package you paid for.
Got nothing to do with how long you talk or what you talk about. If you have a great connection you just know it. If you have to ask then id say no it isn't. But that doesn't mean throw it away either. I suppose ti could nmean a good connection. But not a great one.