Your prayer is valid only when you prostrate on something other than earth or what grows from it in the following cases:(i) If you did so because you did not know that the material you prostrated on is not one on which prostration is required to be performed upon.(ii) If you did so because you did not know that it is a condition in the prayer that you must prostrate on earth and the material that grows from it.(iii) If you forget and did not pay attention until after performing the prostration.(iv) If you did this out of fear - taqiyyah.Otherwise the prayer is void and should be repeated.
While you form the intention of ghusl, with the aim of seeking closeness to Almighty Allah, one should wash his whole body but should start by pouring water over the head, and then wash the rest of the body. You can also perform ghusl by placing your entire body under water at once while having the said intention.
Vivisecting an animal is allowed for exploring a scientific fruitful truth. As for bullfights, it is a must to forbid it because of the torture to the animal without a reasonable reason also it includes wasting the animal and it is a religious prohibition