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[EnergyPlus_Support] Convex Zones and Cross Mixing

I am attempting my first EnergyPlus model without the benifit of 
previous DOE 2.1 or BLAST programming experience.  I also do not have 
either of these programs to generate models for translation.  I have 
what should be a simple project to model one appartment in a large 
complex.  I managed to model the space after several trials and it 
runs as an unconditioned space.  I have yet to properly construct 
proper HVAC system that runs.  I have the following questions.

1. The "space" is a rectangle with a small rectangular cutout in an 
exterior wall corner where there is an outside deck.  I tried to 
model a single zone and got the error message "Zone is not convex 
(CHKBKS) A vertex of back surface is above plane of receiving 
surface..." I got past this problem by splitting the unit in half, 
but now I have the complexity of 2 zones.  Am I correct in assuming 
that EnergyPlus is currently not capable of modeling a complex floor 
plan as a single zone if the perimeter is not convex?

2. As I said, I modeled the space as 2 zones and of course got 
different temperatures and moisture loads in each zone.  I tried 
using CROSS MIXING thinking I could generate almost identical zone 
conditions, but although there are slight differences between models 
with and without CROSS MIXING, the zone temperature and moisture 
conditions do not equalize, even when using large exchange flows 
(over 10 ACH).  Should I expect CROSS MIXING to equalize zone 
conditions if there is a large air exchange rate?

3. Where can I find better references for constructing working HVAC 
systems? I have attempted to understand the "system" logic presented 
in the Input Output Reference as well as reviewing the example files, 
most of which are similar basic configurations with different 
equipment, none of which are exactly like my needed configuration so 
I can not directly rob them.  After several trials I have created an 
HVAC system that nolonger generates any error messages, but it also 
does not run.... I must have NODE, BRANCH, LOOP or ZONE problems, but 
I am taking stabs in the dark to fix things.  I can learn this stuff 
if it is written down clearly somewhere and I can not expect this 
user group to be my problem solver.  I do understand that the Input 
Output Reference is probably clear to the people who wrote the 
program, I just need some references to get me over the initial 
learning hump.  I don't expect EnergyPlus to be significantly more 
difficult to understand than any of the several programming and 
simulation languages I've worked with in the past.   

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