I haven't been in T5 since JAL moved over to T3 the end of March this year. It's good to know that they now have a priority lane for First/Business class passengers. Before, the only priority lane that was there was given to crew and military personnel use, not us folks. Of all the times I've been through T5, and I do this about six to eight times every year, I've been able to clear security in less than 20 minutes, and that's without First/Bus priority lane and about 12-15 people ahead of me in the line. That's a very strange scene that was described up there, about the over an hour security check and people getting stuck in line not knowing what to do - the TSA agents kept yelling loudly constantly about what you should do (computers out, empty your pockets, shoes off, take out your belts & wallets if you have them etc etc..) like a broken record, it's kind of hard to miss. I hope that was just an abnormal day.

Customs & immigration - Definitely, if you are in the front of plane, you're going to have a much shorter wait time. The worst I've had was when four flights were arriving at around the same time. It took about 20-25 minutes to clear. With immigration though, it's a hit or miss with the person behind the counter. Some like to make small talk, some ask you a thousand questions, and some just stamp and go. If you're dying to rush out of the airport, you should get GE. For me, I usually get cleared in a few minutes, with only one or two flights arriving in the morning, and no visitors getting piled up in the citizen lane.

As for getting around the different terminals, only T5 is really separated from the other terminals (T1-3). The airport shuttle train is easy to use, with signs telling you where to go right outside when you come out of the customs area. If you are in T1-3, they have multiple signs on the departure and arrival area. The trains run fairly frequently (like 10 min interval) between terminals. After you cleared security, you can move between T1, T2, and T3 by walkways.