QTR-Quadtone RIP

I would like to add/inquire about another factor in the 
smoothness/banding issue.

In a technical article from Epson, the company claims :
"
Halftone printing

In order to simulate varying size halftone dots in computer printers, 
dithering is used, which creates clusters of dots in a "halftone cell." 
We recommend using Error Diffusion when printing halftoning. The more 
dots printed in the cell, the darker the gray. As the screen frequency 
gets higher (more lines per inch), there is less room for dots in the 
cell, reducing the number of gray levels that can be generated.
Epson's (LPI) lines per inch conversions are as follows:
720 dpi equates to 240 lpi
360 dpi equates to 120 lpi
"

Question 1 :
Am I correct assuming the cell is thus 3x3 e.g. 9+1 shades of grey 
available per cell.

I now refer to an article by Rags Garner (http://www.rags-int-
inc.com/PhotoTechStuff/Epson2200/).

The purpose of this article is to find out what should be the image 
resolution vs printer dpi settings to output the best possible pattern. 
I did not bother in the past and simply set image res at 360 and 
printer dpi at 1440 for lack of information and common acceptance. Rags 
findings are that the best image res/dpi settings would be 
288ppi/1440dpi based on a 2200 with 4x24 (96) nozzles e.g. 5x5 cell 
(???). Besides and image of 288ppi would turn to be 144lpi and would be 
slightly below average human "resolution" thus leading to some detail 
loss or pixelisation.

Question 2:
This is the first time I ever come to this settings ? What do you 
think ? It seems to contradict Epson 3x3 cell.

This would assume a 5x5 cell yieling 25+1 possible tones, I would tend 
to multiple this (less 1 for pure white, not drop) by the 3 variable 
drop sizes to make 75+1 shades available per cell. It's seems that 
human eye can perceive about 100 grey tones which would turn the number 
of ink dilution of 3 more than enough.  

Question 3 :
I'm wondering about the K7, but if the above is not too ridiculous, K7 
would not be so usefull (with only gray inks) and linearisation on a 
21stepwedeg sould suffice to prevent banding and provide adequate 
smoothness?

I'm a very beginner, I was just initially looking for the proper 
ppi/dpi settings to print correctly and was wondering about the best 
linearisation process.

Last, while Epson and QTR do not document the screening methods (I hope 
this is the proper term in English, in French it's "tramage") whether 
it is AM or FM (or a mix of both should also have an impact propably in 
the hilglight rendering. Variable dot size call for AM method (dot at 
same distance, different size)so precise setting ppi/dpi would be of 
even higher importance (I feel).

I'm pretty sure I confuse a lot of things : your advise in the settings 
and the best quadtone combination would be welcome.