(SPOILER)Hello Beenaberry,
Let me see if I can answer your questions. In question 1 you state that there are builders who get distracted and start building on other projects. This is true. I, myself, have had the same issues. It seems to me that if you intruduce them to one task at a time, they will work on that project. It seems that if you do not show them other things to do, they don't know about them. This does not mean you won't find them doing other tasks on the island such as laundry or bathing but at least they will stay more focused on what you want them to do and not what they want to do.
The answer to question 2 is yes, sort of. Sick villagers will migrate to the hospital area but won't necessarily lie straight on the beds themselves. When they are sick, they sort of sit or lay around the whole area.
I will answer question 3 but you have to realize that this is my own personal way of playing the game and not necessily the "correct" way. I do not find a chief until I have played the game for several hours. I only find a cheif when my food supply is low and the chief can help. I find, like you, when you find a chief early in the game, you lose a builder or a farmer. I hold off as long as I can.
Children find herbs is a wonderful thing. It helps to progress faster because the children are faster than adults. Are vv3 villagers slower than vv2 villagers? I really do not know the answer to this but I don't think so. I may be wrong but I haven't noticed a significant difference.
I hope this helps you out.