Q1.I recommend you to get Suica for in case ( and am sure that you'll have cases lol!).
Q2. It all depends what you are interested, what kind of experiments you want for adults and your kids too.
Tokyo has many shrines and temples as you might know, and also there're a lot of museums and parks, entertainment parks.
-Shrines and Temples
I recommend Asakusa area.
Sensouji temple is very famous.
If you are coming end of March to early in April, you can enjoy beautiful cherry blossoms all over Sumida river on the way if you take water bus.
They accept Suica if you get in/off at Asakusa pier.
There are 6 museums in Ueno Park, and its very famous for the cherry blossoms.
There is a zoo with Pandas in the same park.
FYI, the National Museum of Western Art is designed by Le Corbusier, and it's been registered as a World Heritage.
How about the zoo and museums, and cherry blossoms if you are lucky?
I remind Disney land and Disney sea.
Also, Hanayashiki in Asakusa, its the most oldest amusement park in Tokyo ( you can say Historical maybe ).
If you want to try Japanese hot spring in Tokyo, Tokyo Ooedo Onsen.
It's not a kind of "traditional type" of Japan, but still it's worth if you are interested in.
If you love to see the botanical garden, try Jindai Botanical Park in Chofu.
It has Jindaiji temple on the back and not so famous as Sensouji.
There's a huge playground as well so that your kids might be able to enjoy.
If you can give me more information about your wishes, I think I can give you more!
Hope this can be your help!