Just got Galaxy S4 few questions.

Hi,

Just got a new Galaxy S4 moved from a iPhone, absolutely love it, best phone i've ever used.

Few questions for you guys,

1. How do I back up all my stuff to my laptop? I have a Macbook if it makes a difference, i vaguely remember agreeing to let my Google account do it when I set it up but I can''t remember.

2. How do I check warranty information? I'm from the EU.

3. Can I edit the bottom apps of "Contacts" etc to "Twitter" etc for easy access?

I've never used android before (only emulator for college java class) so if you have any tips for a new user I would love some I'm a bit confused.

Thanks