The number of stages is an integer parameter - only real valued parameters can be controlled (otherwise the solver would need to solve for an integer value). For a parametric study the same holds at the moment, only real values can be modified.
Not clear on which heat exchanger outlet temperature you mean - can you attach an example?
The problem with the bottoms flowrate is of a complely different nature - something went wrong with the unit of measure. The document contains
<dimension parameter="bottoms flowrate">
<dimension>
<quantity name="Amount">1</quantity>
<quantity name="Time">-1</quantity>
<quantity name="LightIntensity">inf</quantity>
</dimension>
<flags>OnlyMole</flags>
<select dimension="Amount">mol</select>
<select dimension="LightIntensity">cd</select>
<select dimension="Time">s</select>
</dimension>
and subsequently all unit conversions on this value are nonsensical. Unfortunately fixing the issue requires editing the xml, as COFE is rather persistent in remembering unit of measure preferences.
I am attaching the repaired version, but I would like to investigate how this issue came to be - where did you get this column from?
Thanks.