The Cue Level knob is a relative knob which is not supported in Duplex yet, so let’s wait until it will be ready.
Well then, which do you like, setting it to 3rd&4th buttons on the Activator-row, or 7th&8th buttons under the Device Control knobs??
You need to set Renoise’s *XY Pad Device to anywhere, then you can see the cursor point on the Clip Launch-Grid.
See this thread in detail.
Hmm, if such a crash happens frequently, I’ll ask Danoise to check it. Any error message appaered??
I think that the StepSeq app needs to be improved still. StepSeq config can be made even the present conditions, but it may not be convenient enough. Cie’s LaunchPad sequencer or mxb’s padKONTROL sequencer are much better, I think. Let’s wait when it will be evolved a bit more.
Wooow APC80!! 
Well, for giving various roll to knobs, I’d suggested such a 8-knobs device.
Also, we can make “Notes On Wheels” config. It may be interesting indeed.
Btw, you can also edit config files by yourself. Although it may look difficultly, in fact, I have only combined some parts which already be in Duplex. When you are free, you had better read this. 