Interesting post. Lots of questions here.
In the last PvP event with Iron Fist I made it up to 797 points. I thought I would reach 800, but I took a battle when I was at 777 for what said would get me 29 points. I ended up getting 20 points, but that is another rant. 
—basically you need to consider the point values to be estimates. The longer you wait to fight a old que(anything over 15min is considered old, because that person may have fought over 4 different matches during those 15 min.) Those interim battles affect their score with in turn their value to you. This cuts both ways. I.e. you can que a 10 pt match and 4 hours later when you hit it, it could be with 75pts and vice versa. That said, you will quick learn which names can keep their scores and which names will fluctuate in points.
So I break my shield with 20 minutes left. Win first battle but net loss on points due to attacks while I was fighting. Take another fight and win, net loss of 50+ points due to attacks.
So the last 30 min is super intense. everyone is using there best teams and boosting when possible. Even the 5* god whales get sniped in the last 30min. Honestly, If you haven’t que’d up your cc ahead of time. It will be impossible to makeup significant pts, in the last 20min. At most, focus on a 1 match hop inside of the last 15 min. Always assume that if someone can que you, they will attack you.
While shielded I can still get attacked, which led me to believe others can still see me,
— Not entirely true. They already had you que up on their screen. Shield PREVENTS players from queuing once the shield is established. However, everyone who already has you on their event screen will still be able to start the fight. This is why you see either bounces or a defensive win. If I was to start the game after your shield has been established, I would not be able to que you.
With that said, while your shield. Your completely free to skip and setup your targets for when you unshield. this is what most high level players do. They setup their targets for their next hop while shielded. and once unshielded. They only hit the targets they have already defined. Very few people have the roster quality to just float or que and hit targets on the fly.
I just don’t lose points if I’m attacked and my team loses. I feel that’s not entirely true because as soon as I dropped my shield I was attacked faster than I could win fights. 7+ hours sheiled - 2 attacks. 20 minutes unsheilded - at least 6 attacks.
–Many people often wonder why when they are shielded they get no attacks, but literally 2 min after shield drops waves of attacks come. The reason for this is because shielding hid you from the view of everyone who DID NOT have you prequed at the time of the shield. As soon as your shield broke, the entire shard population can now see and target your team.
Why does it allow me to be attacked by 3 or more other people in the time it takes me to complete 1 battle?
the problem here is that the community actually plays the game in a very different fashion than how D3 thinks the game should be played. You can easily mitigate the multiway attacks, but you need to spend some time learning how the community plays the game, so that you can organize your shields and hops effectively. Join a top 100/50 alliance. Those players can easily suggest very simple things that will boost your scores and lower opponent difficulty.
