Well... I can imagine that NEF doesn't get to carried away with fine detail machining, so you've got a few sharp spots here and there. Sending the gun back would just get you another gun with the same sharp spots.
You can file or sand the sharp edges off so they're not so dangerous... if that's something you're into. If not, a gunsmith can do it for you, or, just try and keep your digits away from the sharp spots.
As to the magazine... take a look at the areas I mentioned previously, and if the spring is ridiculously long, cut it down to about 18" and see what you get. I suspect NEF uses a long spring to ensure that the gun feeds shells reliably.
If it's still too stiff, take an inch at a time off and see what you end up with. Don't go shorter than 14" of spring installed, free length past the end of the magazine tube with the end cap removed
. If you don't clearly understand that last bit... take it to a gunsmith.
Look at it this way, even ''super quality'' shotguns have their issues sometimes, so as long as it goes bang every time you pull the trigger... you're doing OK.
Let me repeat that spring part... do not
cut the spring down to an overall length, just the part that is exposed past the end of the magazine tube. M-kay?