I am going to buy a notebook computer soon and this is the first time I am buying a notebook. I have some questions...

1) What is the average life of the fully charged battery if I only use it for net surfing and doing light task?

2) How long does that battery will last? Does every laptop allows the user to change the battery when it become unusable?

3) How can I protect it from damage while traveling?

4) How can I protect it from thief?

Thanks for any reply!