Sir i want to visit China for a week trip upto Kashghar , the destinations include khunjrab pass, kurakal lake and kashghar town .....and i will travel by Gilgit-Kashghar bus .......

1-How much is the visa fee if i visit with my three other friends?
2-What is the procedure for tourist visa ?
3-Is visa compulsary if we visit just upto kashi or border pass is enough ?