In terms of blood and gore, IMHO, the more realistic the better. I don't like how heads explode from a simple bullet in FO3, or how death blows in FO3 and TESIV send your enemy flying, no matter how large they are.
People don't actually fly through the air when they get hit by a bullet!
http://tvtropes.org/pmwiki/pmwiki.php/Main/BlownAcrossTheRoom
...nor would hitting a person with a sword send them flying backwards. We're talking 170+ pounds of meat here. Can you pick up 170 pounds? No? Then your sword certainly isn't going to send them flying across the room.
In terms of swearing, it depends on the word and how often it is used. Too much profanity just seems childish, like you're intentionally trying to impress the teenage crowd, and as I've gotten older, I've lost a lot of the satisfaction I used to get when cursing. Keep it to OLD swear words, like bastard, damn, etc. TES swear words are nice too, so long as they are consistent with the culture. A nord using "n'wah" would be weird, since n'wah is the Dunmeri word for "slave" or "foreigner." Notice how they use the same word for both meanings? N'wah is an insult to its very core, especially since the Dunmer often used foreigners as (sometimes illegal) slaves before TESIV.