mobile

I'm about to order the following two things from Handtec to ship to the US:
http://www.handtec.co.uk/samsung-gal...-sapphire.html
http://www.handtec.co.uk/handtec-sam...k-service.html

Out of the box, can I immediately:

1. use it on AT&T in the US with LTE support?


2. use it on T-Mobile in the US with LTE support? (I intend to switch in the coming months)


3. flash custom ROMs? (is it bootloader unlocked?)


4. root it? (seems like a pretty confident yes, but I'll still ask)

I don't want any unexpected additional steps I need to take in order to do the things listed above. Am I good to go?

Also, if I see defect(s), such as scratches on the underside of the glass that I've read about, how good is Handtec's customer support for me to return for a new one?

From what I've read in other threads, most posts seem to indicate that what I'm ordering will be fine for me, but I'd like a sanity check on my scenario. Thanks!