For your first issue, the two linked reports do not have to be based on the same information map. However, if you are passing prompt values from one report to the other, then each map must have data items in common that can be associated with the prompts.
For the second issue, if I understand the question correctly, the answer is "no", you cannot link maps together. It is possible to set up an olap information map to drill through to detail data. The detail data would open in a separate window as a flat table.