not necessary unless you require the color accuracy

you can manually calibrate it yourself as well, just tweak around at the OSD until satisfied
no difference, all warranty side still goes back to Dell

its just the matter of whether you want
1. buy from LYN/lelong/shop seller, monitor need RMA, send back to them, they send to Dell
2. buy from Dell Malaysia, send back direct to them

depends

you can send it back to them to check, or you call their customer service to send people to your place to check

both side if monitor kaput, you still need to pass it to them anyway

if you can stand the glossy screen, its pretty good

Ultrasharp series, Professional series

they are all matte based

its U2312HM with slightly bigger screen (real slightly) and different panel (AH-IPS)

its good

so far havent seen any bad remarks on them yet, so theyre pretty good
that 120 pixel really makes a difference

wish i could see 25" 2560x1440 vs 23" 1920x1080p though
roughly 4-6 days afaik, faster if youre lucky

EDIT: how much did you get it for? i cant seem to find pricing at Dell Malaysia's site