Questions About i-tunes

[LacusClyne]

I got some questions about ipod, can anyone help me?

i understood that you had to download songs from i-tunes to be able to add to your ipod. But, how fast is i-tunes updated?

take ayu or kuu songs for example, how fast will they have the new release songs? how long after the single or album is out?

Secondly, can you choose the songs from the library to be your ipod or will all songs be automatic be in the ipod?
If we are able to choose the songs, does the library has limited space?