Help: new tank for Julidochromous sp.

Hello all;

Inspired by NetMax's recent post (re: DIY styrofoam sculpture [hat-tip
to NetMAx]), I've conceived a plan for a tank and "sculpture" that I
want to fabricate.

I've got a 55 gal show tank (36"L X 12" D X 24" H) that I'll use, and
plan to stock it w/ Julidichromous sp (regani, marlieri, or other
similar), plus the usual plecos, cory's, and dither fish. I plan to
start with several juvinile Julies.

Questions (assuming adequate filtration, similar to NetMax's setup):

1. How many individuals/pairs of Julies are optimum for the tank? How
many "caves" should I provide?

2. How many dither fish (aside from the Plecos and Cory's) should I
stock? What are good matches for the Julies?

3. The "sculpture" I've conceived will amuse you all, I think. But
the materials I've chosen limit the size of the "cave" openings to
either 1" X 1", or 2" X 2". Given these constraints, which size
opening would be optimum over the long haul?

Thanks a heap.
-Zz