SimVibe Chassis mode assumes that you have a bass transducer at all four corners of the simulator. You can however use it with just two transducers. When you do this, you set your sound card to stereo mode which will cause the front-left and rear left to collapse into the left channel output. The same collapsing occurs on the right.

There is no actual vehicle telemetry data for road bumps. It's something that we calculate ourselves from a variety of other telemetry data. It isn't meant to give you all of the suspension and resulting road texture. It attempts to just give you the notable bumps and events such as curb strikes, etc.. The Front suspension bumps are complimentary. They are different frequency ranges and while they do include some bumps, they also include additional other details.

In your configuration, with only two transducers, you can probably remove the rear suspension bumps since your wont be able to differentiate between front and rear anyway.

The lock icon allows you to lock an effect. This will prevent cloud-tuning and auto-tune features from modifying that particular effect.