Don Bedwell said:
1.) What is my need for loading "firmware" for the control box? Where do I get it? What do I get", How do I install it?
It should already be loaded with Gordon's standard build of the Marlin firmware. No need to load new firmware.
2. Do I use slicr or Host? Host appears more official, is it?
Repetier Host (which I like, personally) is primarily a program for controlling the printer and the overall printing process. It does, however have some nice integration with slicers - after loading an STL file into Repetier Host - you can (after setting up your preferred slicer) run the slicer from within Repetier Host. There's a big button that says "Slice with Slic3r" (or whatever other slicer you may have configured Host to use). After slicing, you can just hit "Run Job" and everything should happen - hot end will heat, printing will start.
3.) Do I use USB or Flash Card?
I prefer USB but I have heard there is some danger of the printer getting confused if the PC happens to be very slow and/or very busy during printing.
4.) Can I dry run a g code program or does the unit have to have filament loading into?
gMax doesn't know if there's filament or not, so sure, you can dry run.
5.) Is there a way to see the text of a g code program?
Yes, there is a nice, full-featured g-code editor built into Repetier Host.
6.) Is there ANYTHING (aside from dropping the unit) that I could do by all this trying that would harm or break the unit?
It's easy to tell the Z-Axis to go too high, in which case the carriage can crash into the top crossbar, the motors will keep turning, and your X rods can be bent (don't ask me how I know). Most other travel is limited by endstops and assuming they're set up correctly they'll prevent damage. Repetier Host has an Emergency Stop button that's always visible.
Best of luck,
Julia