[Android Q&A, Help & Troubleshooting] Habbit:
What's up guys! I got this pretty cool gig in Japan that I will start in mid-May that's going to last a year at the very least (the American working now with the company said they wanted him to come back for another year, but he had other things here he wanted to pursue.) Anyway, I have quite a few questions and concerns regarding my cell phone service here, as well as my future service in Japan.

Here in the US:

I am not one to resist change... hell, I'm moving halfway across the world (Hiroshima) in a couple of months... but if there is one thing I do not like doing it is most definitely getting a new cell phone number! I have a five week (paid) vacation in December, and I would like to come back to my good ol' T-Mobile HD2 for that month and if I am only on the job for a year, I'd like to come back to the same number. But that's not important, and I don't want anyone to focus on that (like I know some will initially), the question is what is the cheapest way I can go about keeping my current number? As I mentioned, I am currently with T-Mobile, so I'm thinking the cheapest and easiest way to go would be to switch to prepaid after my contract expires? Any other suggestions?

Over there in Japan:

This is the more complex situation. I'm still reading up on the wireless phone service in Japan, and it is quite a bit different from the system we have over here in the States, so if someone catches me saying something incorrect, please let me know!

Anyway, I want an Android phone. Keitai are unique and all, but when it comes down to it, I'd like to be able to keep sync my contacts to Google and use SMS (possibly) to communicate with my family and friends here in the US. The next time I'm in contact with the American who works for the company I'll be with, I will ask him what service he and his co-workers use... though I suspect it's SoftBank, because I believe he has an iPhone. If that's the case, the question of my service provider will (reluctantly) be answered as, and someone correct me if I'm wrong, SoftBank users can talk to other SoftBank users free while being charged when talking to people on other providers no matter what time of day? That being said, for those with the experience, how important is it to use the same provider as the majority of the people you talk to? According to subscription numbers, SoftBank greatly trails docomo in number of subscribers, however I have read online that most people I would likely be communicating with will have SoftBank... very confusing.

The next major question is, of course, which Android phone should I purchase? This is a difficult question because if I am only over there for a year, I would like to be able to bring the phone back to the US and use it. I also would prefer buying a phone that has a decent-sized developer community... Obviously the Galaxy Nexus and the Galaxy S II HD LTE come to mind. The international versions of the phones are able to run on UTMS 2100, which (correct me if I'm wrong) means I should be golden for 3G use with AT&T/T-Mobile AND docomo/SoftBank (I don't really care about LTE at this point of its life.) If all that is correct, then it comes down to which phone to buy... the Galaxy Nexus is sweet and all, but the Galaxy S II HD LTE is better equipped... and I'll be running CyanogenMod 9 on whichever one I buy anyway, so software is not an issue. Decisions...

Last, but certainly the most important question I have (in my opinion), is what will be the cheapest way to communicate with my family and friends in the US while I am away for a year? I haven't done much research into this yet, but what are your opinions... Skype, Google Voice... there are some Internet texting options available on the market that may give me the ability to text back and forth, but some of those apps are proprietary. Does anyone know any apps that will give me the ability to text people who don't use the app or have dumbphones? I have no problem spending a bit of money, but I'd like to find the cheapest way possible to keep in contact with loved ones.

I know this is super long, but I want to be thorough in my research and understanding of the environment I will be moving to within the next couple of months. Thanks for taking the time to read and response!