Digital BW, The Print

Just made the switch from UT14 to Eboni-6 on my 1400 and have a few questions. I read Paul's PDF and the read-me files that accompanied his PS and QTR curves, but I'm still a bit confused. In terms of background, I've used UT14 for years with great success (mostly with QTR but sometimes with Photoshop), but was intrigued by the extra smoothness promised by Eboni-6. My 1400 prints a perfect nozzle check, although the Y channel is very faint (see question below on this). I was very careful to ensure I loaded the inks correctly in the carts.

General question 
- I understand the Y position ink is very light, but it is so faint when I do a nozzle check that I'm wondering if there's a clog in the cart. There are no gaps in the pattern when I examine it closely, but is it really so faint as to be barely visible?

Photoshop questions
- Should my images be in RGB or grayscale before applying the PS curve? I'm getting warm, muddy results in both.
- I've had excellent results with UT14 with simply applying Paul's neutral Photoshop curve, but do I need to make an ICC with a partitioning curve to get a decent test pattern with Eboni-6?

QTR questions
- I copied Paul's QTR profiles to the `Quad1400-MIS' folder and was able to open and create curves for all profiles except `Eb6-PaSmBW-qtr2880-lin'. This last curve repeatedly gave me the error message `Invalid linearize curve – not constantly increasing. Curve creation failed.' Thoughts on how to fix this? This paper is probably the one I'll use the most.
- I printed a test pattern on Premier Matte using the Eb6-EpsHPn curve but it was muddy, mottled, and inaccurate (e.g. 60% was darker than 75%). 

Thanks in advance,

Mark