Must be a very holy shower than if such thoughts can come while showering. My only thought during showering is usually whether it is hot enough, or whether I should be using one of the three brands of shampoo that seem to have made it's way to the rack, even though my hair is only 1 cm long.
1. I am no Japanese so I cannot answer Shintoism. From a Chinese perspective though, Taoism, Buddhism and Confucianism have been so intricately woven in our culture and belief system that most people are unable to distinguish where one starts and the other ends. Though there are obvious things like the Yin-Yang which is a Taoist philosophy and Ku which is the Buddhist philosophy, everything else blurs because the three paths have been embracing each other for over 2000 years and until recently because of the coming of Christianity and Islam, have not sought independent stridings from one another.
To make it simple, original Taoism and Buddhism emerges from two completely different line of thinking and two totally different cultures and worldview.
Buddhism emerged from the Hindu and basically pan-Aryan intellectual Hellenism stretching from Greece all the way to India. As a result, Buddhism incorporated values and world views native to this system. For example, the swastika and the wheel of change, the idea of rebirth and reincarnation, philosophies like that of self and impermanance, the eight fold path and the 4 noble truths and the three states, the middle path, fragments of concepts like salvation as a result from the influence of the mystery religions, etc..
Taoism on the other hand emerged from an older philosophical movement starting from the time of the Xia and Western Chou dynasty. Taoism emphasised unlike the than Hellenistic philosophy which focused on freedom from suffering or complete embracement of deities like Serapis or Mithra or something or deep intellectual philosophical pursuit a very different approach....the return to the simple and to live in time with the Way. This resulted from the than beauracratic Chinese governing system which focused a lot on order and hierarchy which Taoism sees as counterproductive to the path of Enlightenment and Immortality. This approach of blending spiritual life with mundane daily living which is what Taoism is about was something so alien to pan-Aryan philosophy than, which focused on deitic worship, salvation by somet deity, monastic pursuit etc..
When Buddhism came to China, the original Chinese saw it as some form of Taoism and because of this, the two schools could come closer to one another. This is helped with a confluence of certain similar philosophies like the middle way of Buddhism and Balance in Taoism. Therefore, even up till today, most Buddhist and Taoist schools among the Chinese, Koreans and Japanese are actually practising a varying blend of the two concepts with Confucianistic values.
2. Fighting monks emerged in India long ago, but never became popular till 800AD in China when Buddhism was on the verge of being annihilated. 700AD to 800AD marked the peak of Buddhism in China, and also the peak of lavishness in the monastic system. The monks nearing 800AD were living life so luxurious that people were sending their children to live in monasteries just to have a comfy headstart. This was bad for the economy and also as the monks were living such happy life, they neglected their primary task to society which are....to guide, to assist, to help.
As a result, support for them declined and at the same time, the nation was assailed with the first wave of barbarians from south and west. In many places, governance collapsed due to internal struggle and foreign assailing. The monks were called upon and as a result, the fighting monks were reformed. Not to harm, not to kill, but strictly to defend the people and the Dharma. The fighting monks according to the ideal will only attack if many people are going to be harmed through non-action, but if only they themselves alone will be harmed and others spared, a lot of them, as history recorded, kungfu masters of the highest degree, let people harm them without retaliating.
Because of this philosophy, fighting monks becomes part of the folklore as defenders for the people.