Believe me, the Welsh speak Welsh, they also swear in it; I can tell you that from personal experience.

Not down south around bridgend, newport and cardiff way. Meeting someone who speaks welsh is something of a novelty where I live, even the majority of my friends can say more in other langauges than Welsh. Maybe its different in mid wales and the north but the two places I have lived in the south have very very few welsh speakers, off the top of my head I now as many people fluent in polish as welsh (two incase your intrested) When I still went to school a girl came joined our year who could speak welsh and it was a novelty to everyone, outside of her there wasn't a single fluent person in my year.

Also less sure on this one, but im sure a fluent friend told me there are no swear words in welsh, you could construct an insulting sentence but theres no actual swear words... my memorys a little hazy there though...