Ramayana doubts???

Today P was watching Pavanaputra hanuman and the following doubts were raised my P. And i seriously didnt know the answer:

1. Why did Rama kill Vaali from behind the tree? Why didnt he fight with him? Though i knew the reason that vaali would gain his enemy's power , i didnt justify Rama's act. Though there are explanations for that, nothing came to my mind at that time. If anyone can explain, please do...

2. In the cartoon, Hanuman is shown as Siva's incarnation? is that true?

3. Along with Hanuman , so many other people go in three other directions in search of Seetha. If Rama doesnt know the where abouts of Seetha , then how come he gives the sudamani to Hanuman to be shown as a symbol when he meets her?

4. Isnt unfair on the part of Vibishanan to reveal the secret of Ravanas "uyirnaadi"?


Can anyone clear my doubts???????

UPDATE : Got little hanuman book for P and in that the story goes as follows:
Anjana during her childhood days disturbs a sage and he curses her. The curse is such that the moment she falls in love she would turn into a monkey . So, she prays brahma and serves him. Brahma happy with her service tells her that he cannot remove the curse and the only option left is to to give birth to lord shiva. So, she does as advised.
Book name - Little hanuman
Publisher - Seasons Publishing