I am new to iphone and itouch so i have some question about syncing with iTunes.

I currently have Itouch and i am syncing it with my windows vista computer with iTunes library. I have purchased some songs and applications from itune store.(app store)
i have install this songs and applications(games) on my itouch right now and everything works fine.

Now I am going to buy Iphone this week. And I am going to use same computer to sync music on iphone.

so my question is here:
Can i sync my old purchased songs and applications(games) on Iphone?
and in future if i purchase more games and songs from apps store then can i install that games on both Itouch and Iphone? or do i need to purchase it again to install on other device.

Please help me with this question.

I am sorry if this question is already ask before.(i search for it but did not find any answer.)

Thank you in advance.