No firmware to worry about here. The RTL-SDRs can be used as here. The SensorGnome software does some trickery with RTL-SDRs to match it to 48kHz after the fact.
No I don’t use them. Others on here have more experience with bandpass filters and whether they help much, but in my limited experience those situations aren’t typical. But again I’ll let others who have used them much more regularly provide better context.
We try to evaluate whether noise will be problematic before installation. It’s not a fail-safe since it’s just a snapshot of the noise profile at any given moment. And even then sometimes new noise sources “ruin” previously good Motus stations.