Erich-
Thank you for the link.
That article pulls together most of what I'd learned the hard way and gave me a missing piece of the puzzle (Filter Deleted/Unavailable Projects in Debug Configurations). It seems that, even though it wasn't showing up, one of these hidden debug configurations was still being used (due to other project configuration problems?) which made everything fall apart upon launch. (This explains why I kept seeing the old elf file reappear.)
Furthermore, I suspect that workspace folder settings problems were contributing to the difficulties I was having in resolving this problem. For testing, I would import my “known good” project from a backup workspace into my active workspace then delete the project when it went bad. I repeated this process dozens of times all in the same active workspace. Then, at one point, I closed KDS, deleted the active workspace, restarted KDS (which triggered the creation of a new active workspace), and again imported my “known good” project from a backup workspace. This reduced the variety and frequency of strange errors I was having (missing files, etc.) and in concert with the information in the link you provided, a resolution to my issue soon followed.
I managed to reproduce my solution in a sequence of steps and will include documentation of it here for the sake of others who may experience similar difficulty.
(01) (Project Explorer --> <OldProjectName>) : Rename <OldProjectName> to <NewProjectName>
(02) (Project Explorer --> <NewProjectName> --> Properties --> C/C++ Build --> Refresh Policy --> Resources) : Delete <OldProjectName> and add resource <NewProjectName>
(03) (Project Explorer --> <NewProjectName> --> Properties --> C/C++ Build --> Settings --> Build Artifact --> Artifact Name) : Delete <OldProjectName> and replace it with ‘${ProjName}’
(04) (Project Explorer --> <NewProjectName> --> Properties --> C/C++ Build --> Settings) : Click ‘OK’
(05) (Run --> Debug Configurations --> <Icon: Filter Launch Configurations…: Down Arrow>) : Click to clear ‘Filter Deleted/Unavailable Projects’
(06) (Run --> Debug Configurations) : Delete all debug configurations under ‘GDB OpenOCD Debugging’ that apply to <OldProjectName>
(07) (Run --> Debug Configurations) : Select the remaining debug configuration under ‘GDB OpenOCD Debugging’ and change it’s name to ‘<NewProjectName>_Debug_OpenOCD’
(08) (Run --> Debug Configurations --> GDB OpenOCD Debugging --> <NewProjectName>_Debug_OpenOCD --> Main --> Project) : Set to ‘<NewProjectName>‘
(09) (Run --> Debug Configurations --> GDB OpenOCD Debugging --> <NewProjectName>_Debug_OpenOCD --> Main --> C/C++ Application) : Set to ‘Debug/<NewProjectName>.elf’
(10) (Run --> Debug Configurations --> GDB OpenOCD Debugging --> <NewProjectName>_Debug_OpenOCD --> Debugger --> OpenOCD Setup --> Config options) : Set to ‘-f kinetis.cfg’
(11) (Run --> Debug Configurations --> GDB OpenOCD Debugging --> <NewProjectName>_Debug_OpenOCD --> Debugger --> GDB Client Setup --> Other options) : Set to ‘-f kinetis.cfg’
(12) (Run --> Debug Configurations --> GDB OpenOCD Debugging --> <NewProjectName>_Debug_OpenOCD) : Click ‘Apply’
(13) (Run --> Debug Configurations) : Click ‘Close’
(14) (Project Explorer --> <NewProjectName> --> Debug) : Delete this folder (and it’s contents)
(15) Open the project file ‘.cproject’ and replace each instance of <OldProjectName> with <NewProjectName> then save and close the file
(16) (Run) : Debug
Thanks again for your assistance.