From the command line, I don't believe you can get to that value directly. I believe you'll need to parse that from the 'Starting' log message of the most recent job log entries.
As noted, you should first check the job status using dsjob to determine if it needs to be reset. Then only if it needs to be reset, reset it as shown. Lastly, actually run the job.
This is bog standard 'dsjob wrapper script' stuff.
Stage variables first followed by derivations followed by constraints. the stage variable declaration in stage properties,then definition and then constraints. Actually, a big 'nope' to both of you. As answered all those many moons ago, for those three objects it goes: stage variables, constraints ...
Shouldn't matter as the 'before sql' tab will 'fire' when the stage is opened / initialized. Use a single stage with multiple links, not multiple stages each with a single link. And put an annotation on the canvas whenever you do things before or after sql, otherwise they tend to be somewhat invisib...
I'm afraid my first reaction is... what? I've never heard of a DataStage 'accelerator' and wouldn't have a clue who 'they' are. Perhaps it would be best if you explained where you heard about this and what it may be or was used for or something to set the context.