Using underscores is probably a temporary work around. If we consult with Tim and with others using the opaque client we may be able to extend a the types of characters allowed in the problem identifier without hurting the way the opaque client is used for other services. If necessary we can fork the opaque client project and create something that is completely customized to work with WeBWorK. To some extent this is what was done with the STACK engine which originally used the opaque client and then evolved to use it's own moodle module interface.
Answering as best I can without the screen shot reference: the question id is the path to the problem (similar to the path you will see in the WeBWorK homework set editor). It is relative to the `daemon_course` so local problems in the daemon course can be referenced as well as questions in the OPL.
The question version is not used at the moment -- setting it to 1.0 seems as good a choice as any. WeBWorK does not currently have a concept of version number, but other servers using the opaque client do.
Hope this helps.