Amount Users to use WEB AS
I would like to know how many users can use a application on WEB AS in the same time.
this pretty much depends on your hardware and the coding. You can setup WebAS in a clustered scenarion. With this you can have nearly unlimited users - as long as your coding is ok.
This forum runs on WebAS and it is ok to have multiple users on it at a time. So perhaps it makes sence for you to be a little more clear about the recommendations you have, but at the end: if you do not limit the app to give access to only one user and do not block parts of the app for one user for a longer time, there is not really a reason, why you should not be able to use it with 1000 users simultaniously - as long as your hardware can handle that. WebDynpro itself has not problem with that - as you see here in the forum.
Hope this helps you to continue with your work.