I am new to qtp., can anyone clarify my doubts

1.When we use the XML checkpoint for (Web page), The QTP doesn’t allow to select
The web page for the xml checkpoint, it gives the error “ This operation not
Supported”. But I can able to do the xml checkpoint for “files” using the same settings. How can I do it for the web pages?

2.Without doing it manually, is there any other ways to increase the timeout
For the checkpoints.

3.Are there any limitations for the bitmap checkpoint, we can’t able to select
The full page-using scroll down.

4.The Global sheet in the data table accept only up to the character limit
16k, is there any way to increase the limits.

thanks ,(mrartist@rediffmail.com)