yeah that seems to be their dynamic so much just... like different life experiences but i just love how Matt is the one who pulls foggy back on the relativly insignificant immature/jokey stuff but Foggy is the one who has to constantly ground Mat in terms of the big things and is actually established (in the comics if not in the show as well) as being the person who's far more reponsible and skilled at like... every day things like finances and management. it makes for a really interesting dynamic
(also i just have the most delightful imagining of matt giving foggy a little like... hot rod hotwheels and being like 'for the midlife crisis you will no doubt be experiancing soon' and foggys' just like 'wow you shouldn't have')

I honestly wouldn't be surprised if Foggy was the type of guy who just.. adopts all his friends. everyone foggy is ur dad now. u can't fight it its just how this works. ("matt, im not mad im just very disappointed.")

Fisk is powerful and u can really get a sense of his power its just... wow. has an effect.

I'm not sure exactly what you mean by delayed.
I think it's possible that due to his trauma certain triggers (such as experiencing anger) make him disassociate or have trouble concentrating, leading to a more deliberate way of talking. or even regression into his childhood.

separately, I know many people interpret Fisk on the TV show as autistic. (due to behaviours such as the delayed/rehearsed speech you mentioned [as a method of coping with discomfort socialising], the adherence to daily routine or his reluctance to make eye contact).
(in providing this example im not trying to associate autism with 'delay' or 'delayed development', only that interpreting the character as autistic provides a different context for the behaviours you noted)