Comment added by Prof. Hjorleifur Jonsson of Arizona State University:

I can't tell about the last few photos of young women with flowers, but the ceremony is called syo paeng, "collecting soldiers", and is done for collecting the household's soldier spirits (who may roam and damage their fields). The photos are all really wonderful. Young men work themselves into trance (after a bath of hot water and then of cold water) and fling themselves on the pile of burning coals. At the events I saw in Thailand, they all checked each other after coming out of trance, and the lack of burn marks meant that the protection by the household's ancestor spirits was really good. When I saw syo paeng, a spirit medium (who leads the event) blows a magic formula on the participants to wake them up from the trance, and then they dance with the chicken. The bloodiness of some of the offering is to appease the soldier spirits, they really appreciate the spilling of blood and otherwise might not pay much attention. This particular ritual is squarely on the borderlands of what are called ancestor worship and daoism. The trance can be quite spectacular. Supposedly the guys feel hot and in the trance they imagine that the burning coals are a pool of cool water. Some of the photos show how fast the assistants act in pulling the guys off the coals.