Is there a way to modify the config files from the UI? For eg. modify or add a monitor stanza in inputs.conf from the UI?
Also, what all .conf files content we can modify from UI?
Most config files are editable through the UI, although its not always straightforward when your are interested in a specific setting to figure our which UI panel its in.
But, this tool: https://splunkbase.splunk.com/app/4353/
Is quite good for letting you review/edit your config files directly from the browser.