Dynamic Config usage does not count towards the 1M free metered events.
When it comes to the propagation of changes in Dynamic Config, it is officially stated as "near real-time". While there is no precise time frame, changes are typically reflected in the services within 30 seconds of updating, based on anecdotal evidence. However, this is not a guaranteed service level agreement (SLA).
For server SDKs such as nodeJS, the update should happen automatically. Calls to getConfig will start returning the new value quickly. For client SDKs, updates do not occur in the middle of a session to maintain a consistent user experience. If you believe forcing a refresh is necessary, you might have to call Statsig.initialize again.
Please note that the above information is based on expert observations and official documentation, which can be found here.