I'm kind of torn here, because (at least based on the information Majique has shared) a couple of these seem like complaining because a coach is better at the game, or just bugs, but there's a couple that do feel like exploits that shouldn't be in the game.
#1 to me just sounds like superior coaching, at least from the information provided. I've long said GD is a math game dressed up in football pads, and the quicker you can come to terms with the fact the gameplanning/roster decisions that give you the most in game success will not always follow football logic, the quicker you will be able to compete. This is true with any game that doesn't have "stick skill" involved. The "skill" in sim games is figuring out how to manipulate the engine to give yourself as many/more successful probable outcomes in any given situation. "mastering the ones and zeros of the digital game" is literally where the skill gap in a sim game lies.
While, I agree sometimes possessions tend to feel scripted, there's many of times where based of the first handful of plays on the Wiscast I know my opponent is very likely going to score, and I'm just waiting to see if it's 3 or 7. I think the most likely answer to this isn't my opponent is exploiting a loophole, but is because the possession is "scripted". Again, this is a math game, we all want to view it as "real" football and imagine our little pixelated playmakers running around on the field when we watch the cast, but in reality it's nothing more than a series of dice rolls that GD then turns into a description of a football game. Rather than believing some coaches have found some "secret exploit" it's way more likely the algorithm has done its dice rolls and then sets up what it feel to be a "compelling" play by play after, and since we've all watched hundreds of casts by now we've picked up on the patterns/idiosyncrasies that GD uses, particularly the ones that make less sense, to the point where we're pretty good at predicting the outcome of a play in any given scenario.
I'm aware of no "secret formula" or loophole to exploit the algorithm into giving me succes no matter who has the ball, however I have found ways to better understand the "zeros and ones" to give myself more favorable probable outcomes. Many of these make little football sense, my offense is nowhere near realistic, but it's no loophole I've been able to exploit, it's just what I've found has worked based on lots of trial and error (and getting my butt handed to me by a few very good coaches which forced me to get better and/or shamelessly steal what they were using to beat me).
I could be wrong, and maybe Majique just doesn't have all the information here, and that's why it comes across as more "skill" than "exploit" but I just see #1 as complaining about people being better at the game.
#2 is whatever, it's obviously not realistic but been in the game forever, and is relatively common knowledge. Pay any sort of attention to your roster and you'll figure this out quickly, plus there's plenty of threads on the forums discussing it. Get everyone on your roster 30% PT, you should've been doing that prior, but if not I'm glad it's in the open now.
#4 seems like a bug more than a loophole, and while it'd be nice for it to be fixed, it's a hyper specific situation that provides a very small benefit. More nuisance than issue
#3 and #5 are definitely problems that I'm glad have been brought to light and need addressing. As someone else mentioned GD is a talent acquisition game primarily and these aren't better "understanding the algorithm" like #1 seems, they're simply exploits to give yourself an advantage in acquiring talent. While #5 to me is the bigger issue because it can be used across all levels of play, #3 is a big problem for those playing at the D2 and D3 levels.
Being able to gain advantages but avoid penalties for certain recruiting actions, or getting the benefit of an actions without having to pay for it needs to be removed from the game.