In case you were still curious, the original poster from this thread was using 2012.2.920 and Boyan had asked him to upgrade to our LIB at the time which was 2012.2.1022.
As for the 'Recorded Text Content' property, it is expected behavior that it be used as the step's input text in place of the 'Typed Text' property when SimulateRealUser is false (note from step properties that they alternate enabled/disabled when changing SimulateRealUser). I'm happy to see that you've essentially figured this out already and have applied the same binding to both properties, though I should clarify that only one is really necessary depending on whether you plan to use the step with SimulateRealUser set to true or false.
a) You are correct in that only one value will be used but technically only one needs to be bound as well, the appropriate choice being based on the step's SimulateRealUser setting. The fact that two bindings appear in the step description is really due to our naming convention which is expected since you've bound two properties of this step (even though one will not be used).
b) I am sorry to say that I did not find this this difference between your two versions. Please see image DataDrivenType_411 where I needed to bind each separately, the same as with our current version, and both were added to the step's description, related to (a) above.
c) and d) I am sorry to hear that you've come across these issues with the newer data binding UI, we are not aware of such behavior. Please help us to recreate the scenario and investigate further, any additional information with regards to the amount of entries in your drop-down collection as well as frequency of (d) may be sufficient in allowing me to reproduce the behavior in my local environment.
As for your original reason for having to set SimulateRealUser to false, I have pinged our developer assigned to this task for any possible update/time frame he may have. Unfortunately due to our timezone difference, this will very likely take until tomorrow to pass along to you.