Advise required re: uploading files to server

hello,
I will soon be writting a php script which allows a user to upload mp3s to a server. The user needs to enter their 'name' , 'email', 'track name', and 'description' into a form , as well as selecting the file for upload before uploading. The form information is stored within a mysql database and the file is upload to a dir on the server. All the fields are required, and the only file that can be uploaded is of .mp3 extension. I expect the average file size to be in the 80mb region. As a result i have some issues.

Lets say it takes about 20 minutes to upload a mp3, i will need some visual repesentation to show a progress bar, so ajax is a obvious contender. Does anyone know of another way to do this without using ajax?

Would it be best to have the form require the 4 fields (name, email, track name and description) on page 1, validate those fields, and then ask for the upload on page 2 due to the time it would take to upload the mp3? I have written a test php file for this and i have all the forms on the one page at the moment.

I will more than likely dynamically generate the page urls to avoid people skiping to page 2 and the like. To avoid someone uploading the same track twice or person x having the same track title as person y on the server i think i will alter the filename on upload. I will add a hash value to the mp3 title. I can probably validate this too fairly easily too actually.

What other secuirty, validation issues would i need to consider? Is a 80mb file too large to upload in this manner? What would you do? Suggestions please.

Thanks