Just to keep the nomenclature straight, we are talking about flight data monitoring, not FDR monitoring. FDM is usually extracted from the FDR, but it can also be picked off from elsewhere in the system that feeds the FDR, especially when it's digital data
Quite. It depends on the sophistication of the FDR whether it can be used to pick up and record the data that you are interested in. Most modern machines can and do, but are not mandated to do so.