"top" would report most of the information you are looking for about currently running processes, how long they have been running, and who ran them.
As for a list of installed software, that is considerably harder. Different distributions have different methods of package management, so you would need to at least support all the major methods. But beyond that, software could be installed from source, or it could have been a binary extracted into the filesystem rather than through an official package (such as Firefox, Adobe Acrobat, etc, etc).
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