1. How can I download a compiled binary onto Maple? (I assume it is FileName_pde.cpp.bin. I need to send binaries for remote software updates without disclosing the sources).
You will need to send the autoreset sequence to the Maple, then use dfu-util to perform the upload.
The bootloader docs specify the autoreset sequence:
This thread tells you how to use dfu-util with Maple:
2. Can I compile IDE while the cpp file is open? (Can use a text editor like TextPad that has both C/C++ format display and automatic file refresh).
Normally, the build directory is temporary. The IDE should autogenerate new ones each time. You can use the IDE preferences to specify a special build directory to use, however.
Regarding a separate editor, the IDE preferences let you use an external editor. This will make it impossible to edit the file from within the IDE, but will refresh it before each compile. That way, you can edit the files in another editor, but still use the IDE to compile and upload.
3. Can I change the target folder for the files to a dedicated folder (rather than the current C:\DOCUME~1\SAMTAL\LOCALS~1\Temp\build4816439826520861001.tmp\)
Yes; see above.
4. Assuming I wish to edit and compile an IDE programmed file with a cpp compiler, which compiler should it be? (I am aware of the fact this will not enable going back to the IDE, and I assume you don't like this question, but I am a curious personality...).
See the Unix toolchain quickstart; it explains everything.
This can be made to work Windows, but it takes a little more effort. I'm not done writing the documentation yet, but preliminary Windows instructions are available on GitHub: