Hi Michael...
0. First, you can look many of these questions in the help file, by selecting the target as webdev (help files are common to all products)
1. If you look at the keyword upload, you'll see that you can put the files anywhere you have access on the server, as you can define a target directory... And of course, once the file is on the server, you can store it in a binary memo field exactly as in windev
2. None if you don't want to use any PHP code... AJAX is managed in webdev directly for most component and the code, but of course, you have to understand the web philosophy to use it correctly...
3. You can debug the server part (locally on your machine or with the remote debug tool also available in windev)... For the browser part, there is no built in tool, but you can use ajax to log on a file on the server
4. I don't think there is a limit in the number on sites on a server... The limit will be in the number of users using the server at the same time, and that depends of course on your hardware and pipe... You can count on several hundreds users on a normal web server... I personally prefer to use IIS on a 32b OS, as 64b AND linux are not supported as well as I would like
5. Yes, you have to buy a webdev deployment license for each server
6. Just a little self promotion...
... Several of these questions are answered in details in my WebDev video courses (ajax, debugging on the browser AND the server at the same time,...) , along with many more that you didn't ask and perhaps should have...
Best regards
Fabrice Harari
WinDev, WebDev, WinDev Mobile video courses