Are either of these guns suitable for raising welts on the chest of a friend?
Yeah, definitely a welt at minimum if not breaking skin… But most likely a broken nose. ( yours). I know, I had a airsoft BB that went through & under my skin on my face & had to get my doctor to cut it out. DON’T SHOOT AT PEOPLE!!!
I would like to know if the face-mask is suitable for paintball, as well as for regular firearm use. You’d probably get laughed off the range, but regular “shooting glasses” only protect the eyes. 
I highly doubt it. While I have never handled this specific mask, other airsoft masks tend to be made out of a more flexible plastic. This will not protect you from the significantly increased energy of a .68 paintball. This construction is likely because you cannot use a proper sighting system or attain a check-weld with a hard mask on (so that EOTech ripoff becomes useless.) From the product description:
Also for any paintball mask, due to the nature of the sport causing one to sweat like a fat pig on a Alabama August afternoon, a thermal pane is almost mandatory. If you are looking for a quality paintball mask that won’t break the bank. I would recommend the Sly Annex
or you could try the Empire Helix
I have the Sly Annex, and while it is not a Dye mask, the thermal lens works quite well in it. I never have issues with fog. I even have a tinted thermal pane lens to go with it, and that makes it almost cheating in low sun.
Then… what’s the point of airsoft?
That airsoft pistol looks like something your friend keeps as a spare so you have one when he blows you away with his “regular” airsoft firearm.