Hey jared74, welcome to Boardworld.
Boots:
I think your plan of action is best. I wouldn't normally suggest purchasing while on an overseas trip, but even worse would be buying boots online without trying them on. It's really important you get boots which work for your particular foot shape. I did put together a boot fitting article
here. It's probably worth reading so you know what to look and feel for when trying on boots in Japan, especially if there is a language barrier.
Board:
There's a few things you need to consider. Firstly, you have to look for a wide board to accommodate size 13 boots. You also said you like carving, freeriding, and pow. The first thing we should talk about is camber profiles. I'm not sure what you already know so I'll start with the basics. Rocker is going to make the board playful, loose, and float well in powder. Camber will give the board stability, pop, and edge hold. In a nutshell, rocker is going to be great in the powder, and camber is going to be ideal for carving.
I think your best option would be a hybrid camber board, unless you feel otherwise. A hybrid camber board will offer you the best of both worlds and a versatile ride. Personally I would suggest looking for something with camber between the feet, and rocker in the nose and tail. i.e. YES CamRock profile. In my opinion they perform more like a camber board with some benefits of rocker (faster turn initiation, float in powder). I would suggest looking at the YES Pick Your Line 161 Wide or 164 Wide. More info
here. It's basically a high performance, all-mountain / freeride board, which is going to be awesome for carving and riding powder. Stiff in the tail, a few mm of taper (easier turn initiation and increased float in powder), directional CamRock (increased rocker in the nose, again for float in powder) - this board is going to carve beautifully and will absolutely kill it in the powder. Honestly, I think this board would be ideal for you.
Bindings:
There's a lot of good bindings on the market. Burton, Flux, Union, Ride, Rome etc. all make good bindings. Look for something fairly stiff (maybe 7 to 8 on the response scale), with good features and comfortable straps. Ignoring price, I would look at something like the Burton C02s or Flux SF45s. Both super comfy, great features, and responsive for freeriding, carving, and tight tree lines.
Also worth mentioning, you will get 9.09% tax back at the airport if you purchase from Australia and take the goods out of the country (must be within 30 days of purchase however there are ways around this i.e. layby purchase).
I hope I haven't confused you too much. Please let me know if you have any questions.
