I would doubt it, since TV programs are copyrighted too - I would assume that includes the theme tunes.
That said, I doubt there would be much comeback from downloading them - it'd not like they are readily available from a paid-for source (as far as I'm aware).
As a dad of a 4 year old I must ask - why in the name of all that is good in the world would you want to listen to the theme of Thomas the f*&^%$g Tank Engine???!?
This question might be influenced by the fact that my son has made me sit through so many hours of TTFTE DVDs that i've developed a nervous twitch whenever I hear that tune (not to mention thinking about the £££s spend on Thomas toy trains, visting Thomas-land for his birthday recently (for which he had a cake with Thomas on, incidentally), reading Thomas books at bedtime - he has about 40 of them! - the Thomas posters in his room........ I even had to sit through listening to Thomas in the car on the way to Thomas-land cos I was stupid enough to buy an in-car DVD player......
**going to lie in a darkened room with padded walls now. I might be gone a while - now where's my medication**...
I guess it depends upon how old the show is and in what country it was made as to where and when copyright must be applied. For example, I doubt you'd get held up for downloading the theme tune to Seasmy Street or the old Knight Rider series. Also, don't forget that unlike tracks from specific artists, theme tunes are regarded as promotional material so by playing them you're helping to advertise an associated product.
It can. AFAIK we don't have any allowance for making a back-up of legally-bought copyrighted material, although I believe there are moves to change that.
I'm sure it used to be the case (and may still be) that even ripping your own CD to play on your MP3 player was technically illegal (although I doubt that anyone was ever prosecuted).