A deep problem is that everything is related to everything else. There is only one topic: the Universe!
However, just like science is divided into many disciplines and text books have chapters it is useful to organize things.
For example, you were interested in the supernova distance measurements. If that hadn't been kept to (nearly ) the one topic and if it hadn't been kept out of others then we'd have to go over it all again for you.
For yourself when you are learning a LOT of new things it might be best to do the same. Stick to something long enough to "get it" well enough to remember it then move on.
To speed things up you can try trusting people too. When someone says that such-and-such has been measured you can take it at face value at first. If you then decide that particular item is very important to any conclusions you might draw then you should come back and dig a bit deeper.
Not all the answers that people will post here are correct. However, there are others watching over their shoulders and if someone does make a mistake they will be corrected in a day or so.
Sometimes you may want to be careful about asking for too many details.
You will, in the end, get references to the actual published scientific papers. You will be YEARS in working through this if not DECADES if you go to that level everywhere.