Check and advise itinerary
 

Here is our plan in Tokyo for 8 days:

19 Nov: Arrive Narita Airport at 7:15 a.m. Stay in Keio Plaza Hotel. Explore shinjuku. Is there any tourist attraction near the hotel?

20 Nov: Shibuya, Harajuku, Meiji Jingu Shrine, Yoyogi Park, Shinjuku

21 Nov: Ground tour: Tokyo Tower, Imperial palace, Asakusa

22 Nov: Disneyland

23 Nov: Ground tour: Mt fuji, Hakone

24 Nov: Tsukiji, Tokyo station, Ginza
(Which place i should visit first and how to go)

25 Nov: Havent decide yet. (Might visit kawagoe)

1.) Can i reach those places by using wifi?
2.) Where to buy the subway pass?

This plan would not have worked for me. Have you consulted japan-guide.com? I think you might find some very helpful information there.

> Is there any tourist attraction near the hotel?
Tocho and gyoen.
http://www.metro.tokyo.jp/ENGLISH/OFFICES/observat.htm
https://www.env.go.jp/garden/shinjukugyoen/english/

20 Nov: Start from Meiji Jingu Shrine in the morning. Then, move on to Yoyogi Park, Harajuku, Omote Sando, and finish at Shibuya.

22 Nov: Disneyland or DisneySea

24 Nov: First, Tsukiji. Then, Ginza and Tokyo station/Marunouchi. There is a direct subway, Oedo Line, from Tocho Mae to Tsukiji Shijo.
https://www.google.com/maps/dir/Keio+Plaza/Tsukiji/
http://www.tsukiji.or.jp/english/accessmap.html

1.) Can i reach those places by using wifi?
http://opensignal.com/coverage-maps/Japan/

2.) Where to buy the subway pass?
There are two subway operators in Tokyo. Moreover, some other surface transportation, such as JR, could be more convenient. There are many pass types and they are updated rather frequently. Check yourself whether such a pass could satisfy your needs. I believe that the best bid is a PASMO or SUICA card.
http://www.tokyometro.jp/en/
http://www.kotsu.metro.tokyo.jp/eng/
http://www.japan-guide.com/e/e2017.html
http://www.pasmo.co.jp/en/
http://www.jreast.co.jp/e/pass/suica.html

Tsukiji is changing radically. The fish market will relocate before you arrive.

http://www.nippon.com/en/views/g00355/

The new Toyosu market, Toyosu Shijo, will open on Nov 7 in 2016. The last operational day of the Tsukiji market would be Nov 2.
http://www.shijou.metro.tokyo.jp/toyosu/
http://www.shijou.metro.tokyo.jp/cal...uisanseika.pdf

Tsukiji could be divided into Tsukiji inner market and Tsukiji outer market. The handover from Tsukiji to Toyosu means the closure of the inner market only. The outer market, Tsukiji Jogai, a destination for a general tourist, will be remained as is.

The early morning tuna auction observation, that is held in the Tsukiji inner market now, will be continued at Toyosu. The details of this Toyosu aution does not seem to be opened to the public yet, except that will be done in the Block 7 of Toyosu, in the south-west to the Shijomae station U14 on the Yurikamome Line.
http://www.shijou.metro.tokyo.jp/eng...#VisitorsRules
http://www.shijou.metro.tokyo.jp/eng...ukijiguide.pdf
http://www.yurikamome.tokyo/file/pc/...ilroad_map.pdf

Toyosu plan to have Senkyaku-Banrai Shisetsu, similar facilities to Tsukiji Jogai. They will be built in the Blocks 6 and 5 of Toyosu, in the north-west and south-east to the U14 station. The opening of the Block 6 facility has been delayed to Aug 2018.