Actors love to act all those death scenes.
It's not so much a thankless task, it's more a job with no thanks
I loathe cheese, it makes me ill.
As any actor will tell you, the hardest thing to do is small parts, because you focus all your attention and concentration on that small part. When you're playing the lead part, you don't have time to think about the whole of it, so you just have to steam on and get on with it.
I hope I'm always convincing when I act!
I was well aware of the fact that once you appeared in Doctor Who as something else, you were ruled out for the part of the Doctor: that was a kind of well known thing in the business.