I always aim to get there 3 hours before, primarily as the queues at certain times can be hectic and others non exsistant!
I have never had issues with taking equipment (I-pod/laptop etc) onto flights, though I usually fly BA/Asiana out of Tokyo so this may differ. Check with your airline as when I have flown with United, they appear to do an extra check before boarding the plane/remove water bought airside from fellow passengers when I've flown with them from HK. (granted I only use them to HK-HCMC, this may differ again..)
Narita airport is easy to navigate, people are helpful and friendly and never had a problem so far (touch wood, I'm back there in July!)
Have a great trip