Hey. Was hoping someone else would reply as I have only purchased from Amazon JP a couple of times. Yes, you have to set up a separate account. Buying was easy enough, just have to convert from Yen.
When searching, use part numbers if you can as translation may not work for words like spanner/wrench etc.
I can recommend Ninja Tools on Ebay for KTC. He has special ordered KTC spanners for me in the past. He communicates well in English and was helpful/friendly. I got stung with import fees though, which put up the overall cost quite a lot. This is where I cannot advise you as I'm not sure if Amazon JP includes import fees or not. I have subsequently only made low cost purchases from Japan to avoid fees. Not sure how many people view this thread. Maybe worth asking in the Japan thread.
www.ebay.co.uk
If you get stuck buying from Amazon JP. I can try to help.