Digital BW, The Print

I am using an Imac G3 and an Epson 7600 with UC Matte black inks on 
Epson Enhanced Matte paper. I have a few questions regarding the 
QuadToneRIP 2.0 beta 8. 

- When I try to print the ink pattern page in calibration mode with a 
resolution of 2880 x 1440 dpi the second half of the page seems to be 
printed over the first half. Is this resolution not supported 
although it appears in the list?

- With a resolution of 1440 x 720 dpi I am able to do all the ink 
limitation and partitioning and the "linearization". But those 
patches of the step wedge where the light black and the black ink 
both contribute to the density have a strange looking dither pattern. 
What is the reason for this ?

- The highlights are very coarse, even when viewed with the naked 
eye. The "dots" are much coarser compared to the output with my 
StudioPrint demo version using the same inks. What could be wrong ?

Many thanks in advance,
Peter

peter baumbach - fine art photography
http://www.pb-photo.com