1) You might not. I almost invariably use T1, so take what I say loosely. Best bet is to rush off the plane and try to get through passport control as quickly as possible. If you see massive queues here, the signs aren't very good. If you breeze past, already things are looking more promising.

Getting back in could also prove a more lengthy process than you may have anticipated. It's likely you'll need at least 45 minutes to get through the departure security cordon and to your gate (in my experience, boarding commences about 30-25 minutes before departure).

Which brings us to the question as to whether you'll have time enough to eat.
Probably no.

However, you may have time to get a take away.
This place does them: http://www.narita-airport.jp/en/guid..._04_tinab.html

Full list here: http://www.narita-airport.jp/en/guid...rite_t2_1.html

If a restaurant is making a bespoke bento box for you, count on 10 minutes for your order to be prepared.

In T1 there's a shop with ready made sushi which would be much quicker for you - the equivalent in T2 may be this one: http://www.narita-airport.jp/en/guid..._08_shiki.html

Oshizushi - usually with mackeral - is usually recommended to travellers. The rice and fish is laden with more vinegar than 'normal' modern sushi and has been pressed in a box, this means it keeps longer. The other kinds of sushi should be eaten within a few hours.

Rather than eat in a rush, I'm suggesting you take your bento box on the plane with you and enjoy it there.

2) As I'm a T1 user, I can only give you the info on the narita airport website.