几个简单的问题.

1.he gave the books to us all.
为什么gave作为第三人称的动词,不加s? to us在这里做什么成分?
2.he is no friend of mine 可否用not a 代替no?
3.did you have much difficulty in finding the house?为什么在本句要用finding?
4.这两句里面many 分别做什么成分?
⑴many of us have passed the exam.
⑵how many do you need?
5.all i want to do is to have a travel中,I want to do是算从句还是短语呢?
6.he gave the children a present each中,the children和a present哪个是宾语?