To answer your questions about which versions to use:
- Eclipse IDE: it should work with any version. I would recommend the latest released version, currently: Eclipse IDE for Eclipse Committers 2018-12 (4.10).
- Target Platform:
it should work with any version.
I would recommend the latest released version, currently: tracecompass-e4.10.target.
- API baseline: it depends on which version of the TC source code you have checked out. If you are using the latest from master branch, you should set the latest baseline that you see, currently: tracecompass-baseline-4.2.0.target.
You should not need to install any of those other features manually. Whatever is needed by Trace Compass is defined in the target platform. After you have opened the target file and it has finished reloading/resolving successfully (and you can see all the feature/plug-in versions under each update site), you should click 'Set as Active Target Platform' at the top right of the Target Editor.
At that point though, your 'development' Eclipse does not contain the required features. In order to run or debug with the checked-out Trace Compass source code, you need to open Run/Debug Configurations... dialog, and double-click on 'Eclipse Application' to create a new configuration. If you select it and go to Plug-ins tab, you can use Launch with: 'all workspace and enabled target plug-ins' by default, but if you choose instead 'plug-ins selected below only', you will see that the Trace Compass plug-ins come from the Workspace (if you have imported the projects from git) and all the required plug-ins come from the Target Platform (ie. a mix of Eclipse Platform plug-ins and Trace Compass's dependencies plug-ins).
Hope this helps, don't hesitate to ask if you have more questions.