Prepare to Upload Presentations

Is there a checklist I can go through before uploading my first public presentation?
Do I need to sign up on authorSTREAM before uploading a PowerPoint presentation?
How can I upload a PowerPoint file on authorSTREAM?
How can I upload presentations to authorSTREAM on a Mac? Is the procedure any different?
What is the maximum size of a presentation that I can upload?
How can I make my presentation description interesting?
How do I add audio to my presentation?
I have created a customized image that I want to use as the thumbnail for my presentation instead of its first slide? Is this possible?
What quality of images or photographs can I use in my presentation? Can I use high resolution images?