"Ham-ass", "idea-r" and british pronunciation

I listen to the BBC a lot... KALW, my preferred local NPR station, often plays the BBC at hours when I do stuff (2-3pm, 12am-5am).

One thing I've started to notice, which I find particularly strange and a bit funny, is the way the British pronounce certain things. For example, the palestinian group Hamas; the British pronounce it "ham"-"ass" while everyone else seems to pronounce it "hahm"-"ahs". Weird. Also, what's with the Brits ending every word that ends in the letter "a" with an "r"? For example, "idea" becomes "idea-r". Boggles the mind.

(BTW, I can't blog substantively lately about much... too busy... so forgive me if I take a break and write frivolous stuff.)