SCOM 2012, create monitor to check Wep app

Hi guys. 

   I want to create a web app monitor over a web application with authentication. The app works something like that:

1.- User access to web app.

2.- User input user and password (typical).

3.- The web application validates the credentials against a database.

4.- If credentials are corrects, user access to a welcome page. 

As you can see, the web app is very typical. 

So, i want to create a web app monitor, so when web app works fine monitor can see the welcome page. In any other case (webserver is down, database is down, webserver works wrong) monitor can't see the welcome page. 

I have a few questions:

1.- Web applicacion transaction monitoring is the way?

2.- How can i register credencials (user and password) in SCOM to login in web app? In dont't see that option.

3.- Is there any difference between monitoring a J2EE based web app and monitoring a LAMP web app?

Thanks