Cell vs. Landline?

Please help me estimate what it might cost to own a phone/line in Japan. The contract would be for about two years, not a tourist rental. I have looked at the DoCoMo site, but can't really decipher it. Here in the US, we ditched our landline phones and only have cells. It's wonderful. Is that a practical option in Japan? Is is prohibitively expensive to make/receive a call to the US from a cell? What about internet service, then? Will I need a phone line for that or use a wi-fi connection? Bottom line, about how much will should I budget for phone service (ideally cell), for me and a second phone to keep tabs on my pre-teen son? Thanks.

Typical cell phone plans cost around 3,000 to 10,000 Yen. It can get more expensive if you use it a lot.

Here in the US, we ditched our landline phones and only have cells. It's wonderful. Is that a practical option in Japan?

Yes, it is a practical option.

Is is prohibitively expensive to make/receive a call to the US from a cell?

Yes. Therefore, I recommend to use Skype or a similar service for international calls:
http://www.skype.com/intl/ja/

What about internet service, then? Will I need a phone line for that or use a wi-fi connection?

I recommend to get an optical fiber connection. It costs around 5000 Yen per month.

Bottom line, about how much will should I budget for phone service (ideally cell), for me and a second phone to keep tabs on my pre-teen son?

About 5000 Yen for your cell phone. 3000 Yen for your son's cell phone and 5000 Yen for optical fiber internet connection. The above assumes moderate cell phone use.

Thanks for the replies Uji. It is starting to sound as if I can actually make it.

My husband and I don't have a landline in our house. My cellphone package with au costs 4,300 yen a month- a fairly cheap one.

I usually use Skype or Skype out to call overseas, even to banks etc.

I know a lot of people who use Brastel cards to call overseas- they seem to be a good option.