i dont think local telco will repair it when they dont have a good techinical people..atleast they will change it for u n claim from nearest apple store..

its never international, you got the meaning wrongly.
iPhones are normally regional warranty.
but I'm just curious about maxis set iPhone claiming warranty in apple store usa.

apple's product will never get a virus

yes. when you plugged in your iphone, right click at your phone (in tunes) and click backup.

yes. all things that are backed up in your old phone will be in your new phone.

synchronize contact is to sync your contact from Outlooks or any other application of window or mac to your phone

2. basically, if you bought the apps, you can just use it on any idevice you have provided that you use the same itunes account

3. im not sure. never done that before.

i have a question. i purchased whatsapp and i accidentally deleted it. how do i retrieve it w/o paying again.

ps i did not do a back up before i deleted whatsapp.