I think its very easy to believe that Fisk had the best body armor money can buy under his clothes. Hell he might have even had personal shielding, or something all said and done.
I think his strength is supposed to be "peak human"....and considering what feats "normal humans" can do in Marvel, I think he's feats were in line with a peak version of that. The simple truth is, humans in the MCU are just stronger and more durable than actual human anatomy would allow, so you have to allow for a bit of "superhuman" when you look at the top conditions.
And no I don't think Fisk is dead for a second. Whether it was some shield device, or fisk actually turned the tables on Maya and got the gun...they definitely have plans for that character in the future, he's too good to throw away.
Ultimately I think this show was one of the better representations of what I thought the MCU tv shows would represent. Just a good old time, with some fleshing of characters, some fun plots that don't ultimately change things TOO much. Ultimately it did a good blend of making Clint both heroic and mortal, and frankly was a better send off for Natasha than her own movie.