14 or 21 day pass? Which train can use JR pass and which can't?

Hi Admin,

I am from Singapore and will be traveling to Japan for the first time, and I am a little confused by the use of JRpass. Below is the list of my question.

1. JRpass can only be use on JR train? How about the city subway like those in Tokyo/osaka etc..? Is there a website I can check which train I can use JRpass and which train I can't?

2. I saw somewhere that JR pass is no valid to be use on NOZOMI and MIZUHO trains, and there are 4 other types of train .e.g SAKURA that JRpass can be used. What does it means? Does it means for example if I travel from tokyo to kyoto, there are more than 1 type of trains and JRpass can only be used on the other 4 types?

3. I understand there is a Nex service from Narita to Tokyo, shinjuku and yokohama stations, Can I use JRpass on these express service as my hotel on the first night when I reach Tokyo is in Ikebukuro.

4. Is getting the Sucia Pass necessary if I already have the JRpass?

5. Lastly, below is my rough plan to travel Central part of Japan for 20 days, kindly help me decide which pass should I get, 14 days or 21 days JRpass. Thanks so much.

Day01 9 April: Reach Narita at 1400hrs, Hotel is at Ikebukuro ,Toshima, Tokyo, Japan. Will probably travel around the City for the evening

Day02 10 April: From Ikebukuro will travel to Kyoto. Hotel at Kyoto, Kyoto Prefecture, was advice to take Nara Line from Kyoto Station. Is Nara line cover under the JRpass?

Day03 11 April: Travel around Kyoto for sightseeing.

Day04 12 April: Change to another Hotel in Kyoto, was advice to use Keihan line from my previous hotel. Is Keihan line cover under JRpass?

Day05/6/7/8 13-16: Will travel around Kyoto, also to Osaka, Nara and Koyasan but will be staying in Kyoto same hotel. So will be traveling in and out of Kyoto

Day09/10 17-18April: Will reach Okayama and staying there for 2 nights.

Day 11 19 April: Reach Hiroshima and stay for 1 night.

Day 12/13 20-21April: Nagoya stay there for 2 nights and travel to Takayama.

Day 14/15/16/17 22-25April: Back to Tokyo, Ikebukuro and travel around the City. Is JRpass good enough to be use in the city?

Day 18/19/20/21 26-29April: Leave Tokyo, Ikebukuro for Fujikawaguchiko and staying there for 4 nights for the Ultra Mt. Fuji Trail Marathon. Will not be traveling anywhere else except leaving Fujikawaguchiko to Narita on the 29 April to take the flight back to Singapore.

So Sorry for such a long question and appreciate if you can help me to see which is a better option. Thanks so much in advance.