Please explain about Japan Rail Pass.

For visitors from overseas, the Japan Railways Group (JR Group) which are made up by six companies make available the special discounted Japan Rail Pass, which offers unlimited travel on Japan Railways trains including super express trains 'Shinkansen' (excluding Nozomi and Mizuho)
There are 2 types of Japan Rail Passes; ordinary and first class (green car) passes. Each of these passes is available as 7-day, 14-day and 21-day passes. They are big bargains.
Japan Rail Pass is not sold within Japan, and an exchange order for the pass can be purchased from JR authorized sales offices and agents in your country. Upon arrival in Japan, you turn in your exchange order to receive Japan Rail Pass at the Japan Rail Pass Exchange Offices in JR stations by presenting your passport. In Central Japan, JR stations with the Japan Rail Pass Exchange Offices include Nagoya station, Hamamatsu station, Shizuoka station, Nagano station and Kanazawa station.

Tell me how to take a Japanese-style bathhouse.

Pubic bathhouses or open-air baths are available at Japanese-style inns, hotels and 'minshuku' or private guest house.  You can take a bath freely any time when bathhouses are open. When you use one day hot spring facilities or deluxe bathhouses called 'super sento', you pay admission fee at the reception after placing your pair of shoes in the shoe box. In traditional hot spring resorts, complimentary communal bathhouses (external hot spring bathhouses) are also available.
  A public bathhouse has separate bathes consisting of a bath for men and for women. After receiving a bath towel and wash towel at the reception, proceed to the respective dressing room. Use either the locker or basket on the shelf for your clothes.  It is a good etiquette to wash your body before going in the bathtub, not to put your towel in the tub, and, to be careful so that your long hair is not soaked in the tub.  When washing your body and hair, sit on the chair to use the shower.  Shampoos and conditioners are provided in the bathhouse.

How can I take a bus or train?

From the airport bus terminal, the bus service which connects major stations and cities is operated.  The bus fare is either flat fare or fare depending on the distance.
You buy ticket at the ticket booth before boarding, or deposit the fare at the fare box right next to the driver seat when boarding in case of the flat fare bus.  When you take a bus with the fare depending on the distance you go, you are to pick up a numbered ticket when boarding, and deposit the exact fare indicated on the overhead digital fare board in the bus when get off. As for the fare box, there are two types; one is the change is automatically calculated and returned, the other is with change maker.
In tourist spots, you can take a bus in the same way.  Convenient discount tickets such as one day pass of Nagoya City Bus are also available. The railways consist of JR and other private railways in Japan. From the Central Japan International Airport (Centrair), trains with many destinations from the Meitetsu private railway station in the passenger terminal building are available. When you buy the ticket for taking a train, please confirm whether you have to buy a limited express ticket (μticket) which requires additional cost as there are several different types of trains such as local, express and limited express trains.
Nagoya City Subway, on the other hand, trains are all local trains.

Tell me airport names in Chubu, or Central Japan region and the tourist spots adjacent to the respective airport?

Airports where international flights arrive and depart and tourist spots in 9 prefectures and 3 cities in Central Japan region are as follows;

●Central Japan International Airport (Centrair) (Tokoname City, Aichi Prefecture) - for sightseeing in Aichi Prefecture including Nagoya City, Gifu Prefecture, Nagano Prefecture, Shizuoka Prefecture including Hamamatsu City, Mie Prefecture and Shiga Prefecture
●Toyoma Airport ( Toyama City, Toyama Prefecture) - for sightseeing in Toyama Prefecture, the northern part of Nagano Prefecture and northern part of Gifu Prefecture
●Komatsu Airport (Kanazawa City, Ishikawa Prefecture) - for sightseeing in Ishikawa Prefecture, Fukui Prefecture and Toyama Prefecture
●Mt. Fuji Shizuoka Airport (Makinohara City, Shizuoka Prefecture) - for sightseeing in Shizuoka Prefecture including both Shizuoka City and Hamamtasu City areas

In addition, in Central Japan region, we have Noto Airport (Wajima City, Ishikawa Prefecture), Shinshu Matsumoto Airport (Matsumoto City, Nagano Prefecture) and Nagoya Airport (Nagoya City, Aichi Prefecture) which are only for domestic flights.

How do you wear Yukata or light cotton kimono?

One of the enjoyments at Japanese hot spring inn is to wear Yukata while you are staying there in a relaxed manner.
The maid at the inn called 'Nakai' can help you wearing Yukata, however, you can put it on by yourself as how to wear is rather simple.
The point is to tie yukata with sash around the waist as yukata does not have any buttons or fasteners. Make sure to wear yukata with the left side of the front over the right. When you feel cold, wear 'Tanzen' or half coat over Yukata.

Do hotels and Japanese-style inns have English-speaking staffs in Japan? Do they accept credit cards? Do they have an internet access?

You can make yourself understood in English basically at most hotels in urban cities or at major hotels and Japanese-style inns in tourist spots, however, this depends on respective places. Please confirm with each hotel, inn or tourist information center.
As for whether credit cards can be used and availability of internet access, please confirm with them as well.

Can I check my baggage while sightseeing?

At the stations and airports, coin-operated lockers are available. Some lockers are large-size types which can accommodate suitcases.  When you use them, the use fee is per day. For extended use over one day, please insert charged coins as additional fee when you take it out.  Please ask whether you can check your bags at hotels or Japanese-style inns where you stay.  Some tourist information centers keep your baggage as complimentary service.

How much cash should I carry?

Japan is still a cash society. In big cities, most of the places take credit cards, however, small amount of cash is necessary for such occasions as buying some snacks at small shops or venders, admission fees, bus fares, etc.
It could be inconvenient to exchange money or use credit cards in rural areas, so we recommend that you should exchange more cash (than you think) at the airport when you arrive in Japan.