Helm has a lot of extensions, here are some popular ones: https://emacs-helm.github.io/helm/#helm-applications
> As an example, let's say I'm new to elisp and I am wondering how to insert a character to a buffer
You can use google as with any other software. If you search for 'elisp insert character' with google the first hit is the insertion section of the manual which tells you the functions:
https://www.gnu.org/software/emacs/manual/html_node/elisp/In...
As with any other software using google you can find things much more efficiently than with the builtin searching functions.