Writing a Lisp: help me decide what to tackle next

Hi! My name is Rein van der Woerd.
I’m currently in the process of developing a Lisp, for both learning and teaching.
My goal is to derive the best possible language from the smallest set of core features. Your answers to these will help me know what will help you learn the most.

Some features require others in order to be implemented in the lisp itself. For example, a package manager would need IO and networking primitives, and ideally a way to handle json. Others may be able to simplify or replace existing features. String Interpolation can be derived from Reader Macro’s, for example.

Would you take a few minutes and answer the following questions? Once enough people respond, I’ll review all of your answers and use your answers, feedback, and suggestions to develop the next few issues and make it as useful as possible for you.

The issues so far: