1. There are sample projects you can download on the main Alias website. You'll need to create a user account first, then go to the Downloads section and search for sample projects.

2. You could create one single scene for your 5 minute animation, but I think it would be a pain to manage that many frames all at once. IMHO, several smaller scenes would be easier to work with.

3. You should look up information on Rendering for final output. That will have been covered in one of the first tutorials that come with Maya.