Very carefully Please see: component criteria.
No. Don't install/activate what you don't need.
Yes, it's all Free / Libre / Open Source (FLOSS). You can use different components which suits you better (legacy data, better features, etc.) Please do share why/how you did this so other can learn and make better choices for their projects.
All Software Components are released under an OSI-approved license. Please see each component page for the specific license.
No. The main use case is to set up a server (virtual or physical) for each project.
Rest of content is still at https://suite.tiki.org/Tiki+Suite+FAQ