Where have all the manners gone?

I'm stuck between a rock and a hard place. I know I appreciate good manners, but where to put the line? In real life, I say "please" and "thank you" and I'm overall fairly gracious. I'm in an online Master's program, and I get thanked from time to time when I explain a topic or point in a way that someone who has struggled with the idea finally gets the "aha!" moment. I also know that it takes a few seconds to load a post that says, simply, "you are welcome" or "glad that worked for you!". Doesn't mean I'm not glad, but it does mean I'm not willing to waste every other classmate's time with a post that doesn't benefit everyone. Is this rude, though?

On the other hand, what to do with people who say, "I'll call you tomorrow" and then they don't? I have a friend who is joining the army very soon. He starts bootcamp Feb 2nd ( I think). He's doing this [stupid] thing in order to go to nursing school, and then get put through PA school. As I'm a nurse, I've given him some advise over the last few weeks. As he lost his house (had gotten laid off from his former job and he couldn't make the payments) and his phone, I have no way of contacting him on my own. I do know he moved in with his best pal, but I don't know that phone number, so at least I know he's not on the streets. On Thursday, he called me fairly late, trying to work out the difference between LVNs (or LPN's) and RNs, as the military was looking at downgrading the education he had been promised. At the end of that conversation, he let me know he'd call the next day, but he didn't. Why the *bleep* say something if you don't mean it? I'd rather hear, "I'll call you soon" instead of an assurance that he'd call tomorrow. Stupid men.

Now what about IM manners? When should one announce that they are logging off? Going AFK? Going to bed? I think I still have "real life" manners and I get jolted when the IM manners take over with some of my friends. I think a quick, announced "gotta run" is far better than the "bloop, gone" sound notification one gets when a friend logs off, especially if the conversation has been active. Maybe I need to not get riled up over this point, or maybe I need friends with better manners?

Addendum: I talked to one of my dear friends today about the "bye issue". I asked why he hadn't said good night. He said, from HIS end, it showed that I had logged off 2 min earlier. On MY end it showed that he had logged off 41 min prior. I've re-learned that even though something says so on the internet, it may NOT be true. I trust my friend far more than I trust an IM service. Really.
Addendum #2. Turns out his laptop "goes to sleep" after several hours of being idle. This is what logged out my friend. I was correct in trusting him. Gotta say, he is one of the most trustworthy people I know.