Is patenting of business methods available in Japan?

Yes. Patenting of business methods is available.
“Program” as well as “computer readable medium” is a statutory subject matter in Japan.
Business methods are allowable if elements that have inventive steps over prior arts are concretely implemented by using hardware resources.

Are Japanese examination guidelines available in English?

Yes. JPO publishes English translations of the guidelines on their English website (see the link below).
https://www.jpo.go.jp/e/system/laws/rule/guideline/index.html

Is English translation of the Japanese Patent Act available?

Yes. The Ministry of Justice publishes translations of Japanese laws (see the link below).
http://www.japaneselawtranslation.go.jp/