1- No and yes, you need that kind of strength for the most part, anyone who trains for a fight realizes that endless work actually does have some relevance as far as transferring.
Weight bearing exercises beat you up a LOT joint wise and bodyweight conditioning is a lot easier on you as far as longevity and recovery.
That said you can increase a lot more athletic components by utilizing weights
Also “speed” in boxing is primarily what you see, your reaction time, and power is more about striking accuracy.
There are a lot of physically fast guys who just don’t have the reaction time. A super fast power clean doesn’t mean you can hit me.
If you want to get faster at fighting, train your skill set, ingrain in your muscle memory and have the conditioning to be able to execute it on instinct even when tired.
That said, hitting the bag, and pads is plyometric in and of itself. I have a few manuals that mention that hitting the tire with a sledgehammer is good because when it rebounds it has a plyometric effect on your muscles. Same as when you hit a heavy bag.
So technically they’re still getting some speed training. (Which is why I dont mind too much skipping speed days if i were to train a fighter personally) You can develop power a lot of different ways.
For a while we had the specificity crowd trying to cash in on things and you still have guys doing shots with cables attached, or boxing with cables on their arms and stuff.
While im sure that has a great effect for a little while… its nothing to build on.
If you need more strength, get strength in the basic lifts and the transferance occurs when you train your techniques. Spending more time punching with dumbbells than hitting a focus mitt will just change your motor unit patterns and fuck up your striking when you dont have weights in ur hands.
front squat, deadlift, and do bent rows… Hit the heavy bag a lot. You’ll see your power go up. Its really that simple. 90% of people can get more power out of improving their striking technique than just lifting anyway. Only a very limited amount of fighters are so technically perfect that lifting is going to improve their power dramatically.
but nothing wrong with trying to increase both at the same time, but you just have to understand what’s important.
Trading lifting for fighting is dumb. Thats like saying im going to do overhead presses instead of practice my jumpshot.
Its really Technique AND Conditioning, mental fortitude, good partners, THEN lifting.
another lifting concept to think about is its not necessarily mimicing the actual movement pattern to improve “specific” strength, but really the joint expression.
for example, a punch starts at your legs (big toe really) and moves across the rest of your body through kinetic linking and culminates at your fist. we all know that.
well pick exercises that are similar if you want to develope that kind of power
the more specific you get you pretty much end up with the 1 arm snatch, 1arm bench and 1 arm jerk being your best bet for exercises
those lifts require strength and speed levels to be inplace already they’re more like expressions of the power that you’ve already built (dont get me wrong they can be tools themselves but still that point remains true imo)
so to build power, build your strength (squats, deadlifts, rows) and then build your speed (DE work with accomodating resistance imo, or jump squat training, plyometrics, etc).
But ok, back to your friends main question… rocky marciano did not seem fucked up at all by only hittin the bag and doing endless amounts of calisthenics and roadwork.
It’s something that is necessary not optimal but is a small part of the equation of fighting. While i’d rate intervals way above it. A lot of guys roadwork wasn’t just long jogs, if you look around for their logs they’d sprint for a while, jog, sprint, stop do some pushups, jog, sprint, etc or if they do 10miles it was at a pretty good clip. And regardless because of the nature of fighting you can get away with being “slow twitch”
look at nick diaz, he does triathalons and smokes weed. Doesn’t touch a weight or worry about being slow twitch.
its a fight not football i think guys get confused about that. The article DJWolf posted about BJ is right…too many athletes not enough fighters.
just my opinion of course so its ok if you disagree, i respect anyone’s right to be wrong 
2- Yes, but from what i’ve heard… and i could be wrong… that lung capacity leaves pretty quickly once they get back down the mountain. I believe but its a good mental thing. Though I dont know for sure, and im of the opinion if it’s worked for so many previously there has to be SOMETHING to it.
but basically i dont know and its my opinion.
