So, as the thread title might have tipped you off, I'm getting ready to take a trip to Japan to visit some friends and do some sightseeing over about 10 days. This is, however, the first international trip I've planned for myself (I'm from the USA, if it's relevant), let alone one to a country where there could potentially be huge problems in communication, so there's a couple things I'm not entirely sure about, and I'd really appreciate the help from people who have actually been there as tourists, rather than expats or natural-born Japanese citizens (not that your help and advice wouldn't be invaluable, and I gladly welcome it, but a tourist's viewpoint is mostly what I'm looking for here).
The first problem is (as always) money. Specifically, how much should I get, and what forms should I carry it in? I have one of those Visa Travel Cards with money on it, but I know that Japan is still a very cash-dependant society, so I figure that walking in with nothing more than a plastic card is asking for trouble. I already have a fair amount on the card, I'm just not sure what target I should shoot for especially given the poor exchange rate for USD->JPY. I know that this is a very subjective answer, but any ballpark estimate would be a huge help.
Another problem I have (or will have, I guess) is communication. My cell phone is simply not going to work in Japan, which is just as well, since trying using it on the other side of the Pacific Ocean would likely require a loan. The problem is, if I want to meet up with friends, it would really help to have a way to call them to set up exact times/places and such. I doubt I'd be using it too much (I'd be surprised if I used it more than 10-15 minutes a day). I've seen a few cell phone rental places here and there, but all of them look to be stupidly expensive, even before costs per call are factored in. Does anyone know of something reasonably cheap? Or would it be easier to just buy a pre-paid phone of some kind, and keep trying to use it next time I go back? (assuming I do, which I think I'd like to) Alternately, if pay phones are wide-spread enough, I guess I could use those, but if trends in pay phones are anything near what's happening in the US, coin-eating communications are dying out, so I'm not expecting much there.
Customs is a scary thing, no matter if I'm leaving home or returning. I'm not worried about the US customs (they've never cared about my stupid tourist crap before, I don't know why they'd start now), but Japanese customs are a somewhat different story. Looking around online, it all seems fairly straightforward, but is there anything I should know in advance that wouldn't be mentioned in the official stuff?
Finally, the plane ride over is about 10 hours, but I'm not suite sure what I should do for those 10 hours. Should I try to sleep, in hopes that the time zones won't break me quite so badly? On the other hand, I've severely neglected my Japanese studies, so would brushing up on the language be a better use of time so that getting around is easier? Something else instead?
Other than this, I think I understand what's going on and what to do (I fully expect this understanding to fall apart about a minute after I step off the plane, but for now...). I know I'm asking for a lot of advice here, but any help or miscellaneous suggestions would be extremely appreciated. Thank you!