Once the parameters are in PX4, they’ll be visible on QGC if they are used, and visible via Mavlink Console if not (used, or touched, meaning some module accessed them).
For new driver, see this: Driver Development | PX4 Guide (main)
For more basic info, see First Application Tutorial (Hello Sky) | PX4 Guide (main) and Module Template for Full Applications | PX4 Guide (main).
Also, consider using newer versions to make it easier for developers to help you.