Please download Dice Player, the best player out there in the market..
If if does not work, I don't know what does..

You need to flash gapps for the market and other google stuff. 

Yes, you can do that without booting up first while still at recovery.

nandroid takes a few min at most.

Last time I restored took less than 2min.

Depend on number of apps and also whether you are restoring from internal or external SD card.
Be patient, just leave it and come back later. 

You store a lot of prawn is it? data a lot

stop quoting him
restart. as far as i remember, when restoring nandroid it will show you what it is restoring, and system wont take thatttt long, it shud proceed to restoring data

Don't think about that, but you should make sure you have more juice than enough when you are playing around in CWM.
If anything worse happens just hope you can go into download mode, it should be fine, it is hard to really brick Samsung phone.

just flash again lor.

restore later if u want.

if got problem backing up nandroid, probably cause ur backup corrupted.

If it has been exceptionally long, maybe you can consider flashing another Rom...and try again..