Mortgage buy to let..

Hi,
I have £25k which i'm fairly sure I would like to invest into a property rather than in savings, although this area is totally new to me.

I have requested the PDF download on mortgages although it hasn't been sent through yet, so have a few questions..

I'm not currently on a mortgage although am thinking of buying to let as I am living elsewhere, but don't really understand how these mortgages work. I understand you just pay the interest?

Do the mortgages tend to be over any length of time in the same way you would choose another mortgage?

What happens if I change my mind part way through the mortgage term and want to live in the property?

Does the depost on this type of purchase tend to have to be a certain % amount?

Like I say, this area is totally new to me and i'm happy to research, but haven't a clue where to start and, as you can see, don't know half as much as I need to so would welcome any help / pointers :)

Thanks