Zenoss' out of the box process monitoring consists of defining rules for what processes you want to monitor (based on regex statements). Once those rules are in place it auto-discovers processes running on all devices and monitors them. It does not however keep track of pids. It does keep track of the status of processes as well as how many of each are running, the amount of CPU, and the amount of memory consumed by each of them. It also knows whether they are running or not and generates an alert if the process fails. It also has Windows Services monitoring support available that does much the same thing but for windows services. There is a trigger system in Zenoss where you can tell it to run commands when it sees a certain event (and can pass properties from the event to the command). You can make use of things like winexe or ps tools on linux to restart windows processes/services, and you can make use of simple ssh scripts to do it on unix hosts.

As far as process requirements/dependencies, that could partially be accomplished with event transforms (which allow you to develop complex event processing rules) and partially via custom scripts.

1. Impact would be perfect for this.
2. Sure, Zenoss can use check_nrpe and NRPE and nsclient can be setup to run commands.
3. It has colors - Red, Yellow, Orange