A. Adding health monitoring involves many choices. An evaluation will have to be performed to determine which monitors will be of real use.
B. Adding generic logging can be done as part of the rework. After the logging pattern has been established, you can add logging as part of any new work and as part of the refactoring process
C. Adding tracing must be done completely and comprehensively before it can be of any use. There is no point in implementing tracing in a single part of the application if you are not going to refactor the application
D. Creating a data collection set in Performance Monitor will provide all the needed information and can be set up in a few minutes