Let me blame it on the spell-checker.

long-ish layover at HND
 

Flying ANA business class from Germany to Sydney soon, I'll have a roughly 6 hour layover at HND on a Sunday afternoon/evening, 4 pm to 10 pm. I've never passed through HND before, so I'm not sure whether the terminal and lounge would keep me busy for 6 hours? Or would you recommend to leave the airport for a quick walk outside to stretch legs and catch some fresh air? If so, would you prefer to take the Monorail to Hamamatsuchō or Keikyū line to Shinagawa? I'm travelling on a German passport, so immigration should not be an issue, but maybe temperatures. As I'll be on my way to Australia, I won't have a really warm jacket or coat with me, so it would be only a short walk outside and hang out around the station. Any thoughts about this layover?

Keikyu to Shinagawa and walk through the JR station to the Atre department store. You would be under cover (for the walk through Shinagawa station) or indoors (in the department store) the whole time. It's not terribly exciting but it will give you a break from the airport. With your arrival time of 4pm, there's not so much to do in the immediate area around Hamamatsucho station. (If you had an earlier arrival, I might suggest visiting the nearby Kyu Shiba Rikyu garden - but I think it will be closing by the time you get there).
Another plan would be to take a Keikyu Airport Express train, which stops at subway stations in central Tokyo. That would put you in an earthier part of town. You could get off at Shimbashi, and join the salarymen in the izakayas for after work drinks and chicken on sticks.

It is definitely possible, just make a plan and stick to it. You don't have huge amounts of time, so don't waver too much.

Specific train from Haneda really depends on where you want to go.

JAL Airlines on ONE HOUR connection at NRT!!!
 

I'm booking business class flights for elderly parents, but the ONLY availability I have is with JAL for SIN-NRT-SAN, with only 1 hour connection. How is this a legitimate routing?

As business class customers will JAL:
1) Offer expedited service for them to jump to the front of the security check lines?
2) Hold the flights if the security check lines are long?

They've transited to NRT, and have told me the security checks lines are really long and slow, which is surprising as I thought Japan should be fast and efficient...

Take a deeeeep breath (or a chill pill)!!!
NRT is one of the best/easiest airports for short connections ... and JL and NH are well used to making sure passengers go quickly from one aircraft to the next.
JL wouldn't sell/offer a one-hour connection if it wasn't legitimate.
1. Business class and frequent flier status passengers receive fast track security line screening.
2. Unlikely - depends on number of connecting passengers to that flight, but JL will deploy staff to incoming gates to speed transfers.

I suppose bad experiences are always possible but in the dozens of times I have negotiated NRT, I have never experienced long. slow security lines. Occasionally, the inbound C&I lines can back up but that is not an issue in your case.

Either way, transit passengers will not go through the regular security queues. They will pass through the transit security area and as noted above, JAL staff will be there to help.

Since you're arriving after sunset, if you've not seen Tokyo Skytree, that's sure worth seeing. Take Keikyu Line / Toei Asakusa Line to Oshiage Station, and you'll be in the shopping mall at the base of Skytree. Even if you don't go up (fee), seeing the structure from the ground is spectacular. Easy access direct to/from Haneda too.

Access by train | Access | TOKYO SKYTREE

Thanks a lot for your suggestions. I think I will stick to Shinagawa station area and hang out there for a while with a bento, just for the simplicity of access to/from HND.
Some quick questions about practicalities: Are there some lockers or left luggage facilities in the arrival area where I can store my small bag for 2 hours? And do ticket machines take credit cards or do I have to withdrawl some ¥¥¥ from an ATM?

I have taken this exact flight combination twice and made it. The first time without any delay and it was easy. The second time I had a 20 minute delay and made it even with a short detour to my favorite candy area. There was a person waiting for me with my name probably to help escort me to my flight, but I wanted to get a certain candy box only available at one place so I went past them.

Lockers
​http://www.haneda-airport.jp/inter/en/premises/service/delivery.html#locker​​​​​​

Ticket vending machines only take cash.

OK, good to know. Thanks for your quick reply.

Traveling through Haneda on separate ANA tickets of international - domestic

LHR - HND
Arriving at 14:40


HND-FUK
Depart for FUK at 17:00


two hours and twenty min.. is this a bit tight?

Assuming you're flying Y with checked bags and no status, you should be fine as long as your flight arrives at gate no more than ~40min late. If I were traveling alone, I would take that chance, because most likely you'll be fine and plus they might be willing to move you to a later flight without penalty (but no guarantees). If it were me and my entire family, I would take a later flight because the potential penalty would be very costly.

If you're flying Y with no status, then it can take a long time for ANA bags to come out at HND. The last two times it took 40-50min from parked at gate till my non-priority bags came out. No line at immigration, but just waited and waited at the carrousel. Priority-tagged bags come out much earlier.

The cutoff at bag drop off at Int'l arrival concourse is 45min (ie, 16:15 for you). As long as you make that cutoff, you'll make the flight.