Here's my $0.02 . . . . . . .
For home made chips and french fries, I'd say scrub 'em good and leave 'em on. Upon completion of cooking, salt 'em with sea salt (I'm on a sea salt kick). For a different twist, cook the chips in olive oil. Not sure what the temp would be, but SuperTarget makes a bagged chip that is nothing more then Russets, olive oil, and sea salt. I love 'em!
As for mashed spuds, I'm not a fan of leaving all of the russet skin on. I've had roughly peeled, with some skin on, and it was good. I'm just not a fan of leaving the skin all on when using russets. When using reds/news I do leave the skins on. That's my preference, anyways.
As long as they're scrubbed well, I don't think there is a particularly wrong way. I'd eat 'em pretty much however they were placed in front of me, preferences aside.