Hi OutOfLine - Thank you. I dug up additional information in case it may be helpful to the Arduino community at all.
It appears the real culprit here is Ubuntu/Linux "MultiArch" which demands that 32-bit files be configured a certain way before it will recognize them. Kind of takes the point out of having a bridge to 64-bit. Because the older "ia32-libs" program seems to make Arduino work fine...but you have to break your Ubuntu install and potentially cause other problems to get that to work. Anyway. Linux MultiArch, at least on AMD processors for 64-bit, is currently not recognizing some 32-bit programs.
The reason this is important is Ubuntu 12.04 is a "LTS" - Long-term Support release where security upgrades continue on for years and you don't have to upgrade to the latest which may/may not be stable because Ubuntu releases are so frequent. 12.04 is supposed to be supported through 2017.
All of that said: The bottom line is Arduino seems to be incompatible with Ubuntu 12.04, 64 bit at this time (at least on AMD, maybe others). The primary reason seems to be that the Arduino "64-bit" program really is not a 64-bit program... At least it has 32-bit architecture files involved; and Ubuntu's MultiArch does not recognizing those files. It behaves as thought they are not even on the computer or at least delivers an error message that says as much. I am going to file a bug report with Ubuntu and hope they look at it; but with Ubuntu it often takes many months for them to get to real bugs. I am not going to pursue the "ia32-libs" solution because that appears to involve breaking dependencies and I seem to have other system issues crop up once I attempt to install "ia32-libs," although the Arduino program does function at that point.
Here is additional info on MultiArch:https://help.ubuntu.com/community/MultiArch
If we research MultiArch and ia32-libs with words like "problems," we can see that most problems involving ia32-libs, which I believe is an older program, are traceable to the MultiArch.