Can I download apps from the US app store if I'm using a different store? Can I download apps from the US apps Store even if I'm currently using the italian store ?

For example, I would like to download Spotify, which is not available in the Italian store:

Should I change credit card? Or can I use the same one?
You will need to create an account on the US store.  Apple probably won't accept your foreign credit card either (at least they do not in Canada), so you need US gift cards to create an account.  Google for more information.