I primarily use the browser on my PC for accessing the forum. As @Adrian noted, it would be nearly impossible to do many of the things I do using the Android app installed on my mobile device. I frequently provide links to content and couldn't do that without being able to easily copy/paste them into comments or answers. There's also the SF.SE Twitter Feed that I've seen and read, but don't follow.
Like you, I'd like to find a good way of following posts that I've read, but didn't respond to because they needed more information from the OP before an answer could be provided. I primarily follow the "newest" questions feed here in the forum, but recognize that the "Active" feed would allow me to see those updated questions and to also vote on newly answered questions as well. I'd like to remember to check that feed more frequently so I can do that. If we all did, perhaps more up-voting of posts would occur in general.
Occasionally I go through the "Unanswered" feed, but often find it frustrating because the first half page to nearly a full page (@ 50 questions/page) tend to be quite old. It doesn't allow me to get to more recent unanswered questions quickly that I'm more likely to be able to respond to.
Like most, as the numbers I see displayed change, I drop in and read the "Featured" questions too, posting a comment or an answer if I can help.
I recently learned about the #askforce tag on twitter. I've seen @LaceySnr post to ask others to look at specific question here on that feed. I'd like to begin using that feed myself to bring attention to questions I've personally been trying to answer, but have been unable to bring to resolution and need other eyes to take a look at. I don't know if enough people visit the chat room to where it would be helpful to post there for assistance with a particular question or not. Its been a long time since I've remembered to drop into chat myself.
Clearly, we have many tools available to us. In my view, by far the best one is the desktop/laptop browser of your choice. To me, all the others are more for keeping up with what's going on when a laptop or desktop isn't available for use. I could possibly see using some of them on a tablet, but since I don't own one, that's a rather moot point.