Do my best to get everything.
The way scoring works is based off of standard deviations and Z-scores. Now please bear in mind I am not a math major so I may confuse some terms. In essence the MASS (some black magi formula) finds the standard deviation of a class and creates a bell curve. From that bell curve it assigns scores based on how far above/below the center of the curve you are. Now How it determines the point value of each persons score is unknown to me (meaning 75 pts is not the "max", it varies class to class and I have no clue why). So for example, a class whose average score is 96 may have a person with a score of 99% get the highest points (call it 69) and the lowest score of 93% will get the lowest at 30. Everyone else gets something in the middle based on their distance from the center of the bell curve. Same process applies to daily rides and check ride scores.
U/F/G/E grades. So individual grades, i.e. how well was a landing or specific maneuver, are graded based on CTS (course training standard) which is found in the syllabus. It defines ranges and parameters that a student must meet in order to receive a G (good). A pattern for example is to be flown -0/+10 kts or airspeed. If the student does this they get a G, if they do really well they get an E, if assistance is required they get a F, if unsafe/unable it's a U. Overall grades however are up to IP discretion. Therefore if your IP thinks that for where you are in the program that you did really well then you might get graded an E. If you suck, enjoy your taco salad (U). What this means is you can have a grade sheet of mostly U's (say it's your second ride) but you seem to be picking things up and are pretty sharp, then your IP may give you an overall E.
Yes individual grades have points associated with them (1-5 if I recall correctly, 1 being a NG and 5 being an E). They all get compiled at the end and run through the MASS. Just like your academics it's based off of standard deviations and Z-scores. Only difference is that there is no penalty for attempting/not attempting a maneuver as it averages out your gradesheets. For example, you do a pattern only where 20 items are graded. Those 20 items are worth up to 100 total points (20*5=100). You average out to mostly Fairs (3 pts) for a grand total of 60 points or 60% of available points. Your bro goes out and does MOA work and has 40 items graded, but averages a Fair rating for most of them earning 120/200 points, also 60%. So in the end it's really points earned/points attempted, then run through the computer (black magic).
At UPT (Vance, Laughlin, Columbus), Phase 1 and 2 scores affect your Track Select. Phase 3 is separate. At Sheppard (I think) they all factor into the overall drop. Flt/CC's have a 20% say in someones final score. It's referred to as Flt/CC ranking and is a way for them to help out someone who has been a solid bro and maybe bump someone down who has been a jack wagon. So yes, working hard and being a bro does help you out, your IP's WILL notice.
As for experience, like all good answers it depends. Ive taught a kid who had 4700hrs when he showed up and he made UPT his b**ch, but he was super humble and a great kid, everyone loved flying with him. Had another student with 1300hrs who everyone hated. And when IP's sit down they do take experience into account. But in all honesty once people hit instruments it evens out, and if someone has a lot of experience, formation evens them out. I wouldn't worry if you have some high time guy in your class. They will not be the reason you don't get what you want, you and your attitude will make/break you.
The last question, I don't know. That's more of a phase 3 question (I taught T-6's).
Hope this helps. In the end enjoy UPT man, getting all wrapped around tiny shit like the MASS and individual grades will just take your focus off flying. Relax and have fun, it was one of the worst/best years of my life. You will have some amazing experiences and some serious bad days, don't lose sight of the prize, it's all worth it.