Looking for software to write a script
 

I am looking for a fairly simple software that would help me prepare a script to produce a travel video. I mean something that will assist me in determining :
1. The overall duration of the film
2. How to construct a story with a thread to make the story flowing nicely
3. How to group the rushes to follow the story or the script
4. How to determine the duration of each clip
5. The narrative aspect and music background
6. Etc

I was about to construct an excel file with the various columns required and fill in the cells myself but I am afraid it would not provide me the guidance I am looking for.

So can someone tell me which software I can find to do the job?

Without spending a large sum, have you looked at this... Celtx - Integrated Media Pre-Production