This sort of answers both questions 1 and 2. Pacquiao's torn rotator cuff had to have some sort of effect on him, the question is just how much of an effect. A torn rotator cuff is a common shoulder injury to anyone involved in athletics; they're often caused by repetitive motions like forceful pulling or overhead movements, they're especially common among powerlifters, and can sometimes be brought on by the simple "wear and tear" or suddenly due to a combo of wear & tear and sudden force that usually afflicts the tendons. There's a pretty broad degree of severity in terms of how large a tear can be and there's debate as to whether surgery or non-surgical management is the way to go; it's not uncommon for people to still not be able to regain full range of motion even after having surgery. While he wasn't at exactly 100%, the consensus was that it wasn't severe as the fight wasn't postponed, so it gives me the impression that the injury didn't have any significant weight in the outcome; the simple fact of the matter is that Mayweather decisively and dominantly outfought Pacquiao. I thought the fight was pretty damn dull, it certainly didn't seem like some sort of super fight in my eyes, because Pacquiao was just simply outclassed; I read that Pacquiao only landed somewhere an average of about 15% of the punches he threw over the course of the match. Like so many boxing "dream matches", there was a ton of hype and the fight didn't come remotely close to equaling said hype. I've no real interest to see a rematch, it took them 5 years of negotiations to finally get the first one and it most definitely wasn't worth the wait.
As to where they both go from here, I'd say both men are close to the end of their careers.
Pacquiao's 36 years old and that's pretty old for a boxer, or for anyone involved in contact sports when you get right down to it. He's gotta professional record of 57-6-2 and is among the biggest names in boxing. He's also won a total of 11 World Championships in 8 different weight divisions, the first and only boxer to be World Champion in that many different divisions. He's someone that's well respected and very well liked among boxers, boxing insiders and fans from all over the world; there's definitely nothing he has to prove.
Mayweather's 38 years old and, as I said, that's pretty old for someone that participates in contact sports. He has a perfect record of 47-0-0 and if he retired tomorrow, he'd be one of only 8 fighters in history to have never lost a bout or had a draw. He's also certainly no slouch in terms of championship accomplishments as he's a 16 time World Champion in 5 different weight classes. As a person, I'm not a fan of the guy as he's beyond arrogant, but that's incidental when you take into account the fact that he has a well documented history of homophobia and domestic abuse. Despite the fact that I think he's a lousy human being, he's a fantastic boxer and will quite probably go down as one of the greatest of all time.
Both these men have more money than any sane person would know what to do with, as Mayweather and Pacquiao have net worths estimated at roughly $400 and $200 million respectively, they've been dominant fighters with numerous accolades, recognition and championship wins. Neither guy has anything to prove to anyone.
As to what this fight means to boxing as a whole, probably not a whole helluva lot. There've been a lot of "dream matches" and "super fights" in boxing and while this one generated a ton of press and hype, it's hardly gonna be viewed as an all time great. Frankly, it wasn't that good or competitive of a fight anyhow, at least not in my opinion. Ultimately, what this fight was more than anything else was a marketing and money machine designed primarily to generate as much revenue as possible while sacrificing the heart of the sport. At one time, boxing as a whole was highly revered but it's been rocked by too many scandals over the years and too many vultures like Don King have helped eroded the prestige of the sport. What's happened to boxing is just about the worst thing that can happen to any sport: it's been turned into a business that's ultimately designed to milk as much money as possible. I don't mean to suggest that making money is a bad thing, but it's really the only thing in boxing and what's been sacrificed is sportsmanship, athletes who conduct themselves like gentlemen rather than guests on an episode of Jerry Springer and simplicity. Once upon a time, you fought whomever your top contender was if you were a champion; today, it's often become a series of political moves, negotiations, ducking, dodging, maneuvering and wrangling to set up a title match.
