Few general questions regarding Match...

Basically I am happy with all the music on my iPhone 4S which I regularly sync with iTunes, now am I right in thinking that unless I go into Settings - Music - Then turn on iTunes Match then everything should stay the same? basically I don't want to have duplicate songs from the cloud showing with music already downloaded on my phone? Ive heard that people subscribing to match have messed their library up on their phones!

On the other hand, on my iPad I don't have any of my music due to not having enough space, so if I turn iTunes Match on am I right in thinking that I will have access to my whole library but able to stream it (like Spotify) and also not taking any space up on my iPad?

So overall I want my music backed-up incase anything went wrong with my laptop and the ability to stream my music on my iPad.....would you say its good at accomplishing this ie.. worth it?

Many Thanks