Will you please give me advice on my video project?

I have a video project due in a few weeks and I'm shooting it with my friend's Nikon camera. Pretty cool camera, not too big, not to fancy. Anyway the camera has nothing to do with it. I want to shoot a good video

SIDE NOTE: It's a video for a trailer. Like a movie trailer only it's for a book.

So I have a few questions:

1. What is a good and free website I can use to edit the video that will not be slow on my computer or send viruses?

2. Going with the first question, is Windows Live Maker sufficient?

3. Approximately how long do you think it will take to edit this video, that I estimate to be about 4 minutes long. I want it to be as close to a movie trailer as I can get, but free!

Thank you so much for anyone who took the time to read this and help me out: D

I have no idea on your first 2 questions because I only know pro software. Depending on how you shoot it, from start to finish on the post I'd give myself 24 hours of work as a minimum. Sound is another matter. Edits can vary greatly depending on how you shoot and how you plan to edit.