So on these 2 things...
Before you leave the airport get a tourist Suica or Passimo card. Use this for all your travel needs.
The metro has English translation. You can use this site to help you get from point A to Point B. You walk up to the ticket machine, change it to English and you are good to go.
Route Search | Ekispert for web
https://share.google/UWpdBObbHkT34JDZs
Then you just beep the card through the departure gate and beep it through the arrival gate. If you need to reload jt, there are reload machines right by where you buy tickets. When you go through the gate it tells you how much is left on the card.
Mobile data, check with your current provider. At&t is $10 a day but caps out at 100 i think. (I don't remember) if you have other phones on your plan that are going with you, it is $5 per day for them and also caps at a certain amount.
For me, with 3 phones, it made more sense for me to just notify AT&T. You don't need anything special, your phone just joins the new network, and you are good to go.
Added bonus info: Fly ANA. I have been flying to Japan for 20 years and during that time have used all kinds of airlines. The last couple of trips I have use ANA (flying into Haneda from Seattle) and I told my wife, I will never fly to Japan any other way. The headroom, the legroom, and they were serving me free sake soooo that might be influencing my decision a bit. ANA also just announced deals until May 31st so might be something to look into.
Editing to add they jacked up the prices so much for the JR Rail pass that it might not be worth it unless you are traveling from Hokkaido to Okinawa...