Hi Mukesh,
1. Crosstab reports are like autogrouping: every data element must either be a summary aggregate or a grouped column (with the exception of associated data - I haven't tried this but it should work). Including other data into the report will effectively break it.
2. Hotfiles are traditionally used to resolve tricky 1-to-many join issues, to combine data from different data sources, and to handle what would normally be multi-pass SQL instruction. The first problem (1-to-many issues) is better handles with a table view. The last problem is handled now (version 6) with a technique which answers your third question. The second use remains the area where hotfiles are still useful.
3. In version 6 you can use a report as a data source for a second report. Create a report and save it. Open the catalog as Creator and add the report by going to Tables on the Catalog menu and clicking the Hotfiles radio button. Then browse to the directory you saved the report to. Add the report and then add any required joins. The report will run on demand and pass current data to the second report.
4. Scheduler can only save to Formatted Excel via a macro using SendKeys. See another posting here for a discussion of that technique.
5. Cascading prompts are created via a Report Picklist prompt. These are separate reports using prompts that guide the user through distinct prompts that narrow the available selections based on the users input. The help files provide some useful examples based on Great Outdoors.
