Woah, those are a lot of questions there!
Where do you find information? There are links on top that can make it much easier to navigate. Click on "new posts" to see if there are new posts since you logged in. I use that frequently and it helps a lot
Some threads are private (Moderator forums, Helper forums, etc.)
You need to get a certain amount of posts to become a "full member." As of right now, you are a partial member because you only have 3 posts. Once you're a full member, you can do much more!
I use a setting that works well for me. Maybe you will like that as well. It's when you are automatically subscribed to every thread that you post. So that way, you can know if someone has responded
1) Go to Quick Links on top of the link. Then go to Subscribed Threads.
2) Once you're there, on the left, you need to scroll down until you see the link Forum Settings. Click on that.
3) Once you're in Forum Settings, you'll see Messaging & Notifications. Go to the Default Thread Subscription Mode and in the drop-down menu, click on Instantly, email notification.
4) Then scroll down to the very bottom and click Save Changes. Make sure to do that!
I'm sure there's a faster way then that, but I do that way
So now every time you log in, you can go to the link on top and click Quick Links, and then go to Subscribed threads. And then there will be the threads that you have responded in
And if they are bold, it means that someone has responded to a thread that you posted in!
Hope this helps