Newagekat -

1. I think your best bet here is per-category stylesheets.
Set the categories box to display: none; in your main stylesheet,

#categories {display: none;}

and make a stylesheet for each top cat named like c_1.css containing the rule

#categories {display: block;}

2. Add to your stylesheet

.categoryListBoxContents {display: none;}

3. Admin settings... If you don't want them removed from the top categories, you could do the same display: none; / display: block; routine as described above, using the same c_1.css stylesheets.

4. This one would be difficult, except for the abilities of the newest Cat Dressing version. Are you wanting a column of brand subcats, and a column of fibre subcats next to it?
Making "groups" for those two categories will let you treat them separately for positioning. (You will need a group for each of these subcats under each top cat.)