Earlier quoted context omitted.
Scrollback is implemented as a patch: http://st.suckless.org/patches/scrollback
This. Also, one should keep in mind that having to apply personal patches is perfectly acceptable for suckless software. In fact, for the very same st, to change font, colour scheme, or hotkeys/shortcuts - one has to edit config.h file and recompile. There is no traditional text config file or "Preferences" menu. This might sound bizarre at first, but actually works as well as editing a text config file: config.h is…
No, you don't have to recompile it. For shortcuts, sure, but I haven't used any st shortcuts besides font size +/-.
Colors can be changed via the shell e.g. https://github.com/chriskempson/base16-shell and the font is passed via the -f flag.