Provide helm completion on headers of all org files contained in `org-directory` and allow executing diverse actions on headers.
Provide helm completion on headers of the current org buffer.
You can refile one or more headings at a time.
From a org buffer, to refile one heading, move the point to the entry you want to refile and run `helm-org-in-buffer-headings` or `helm-org-agenda-files-heading`. Then select the heading you want to refile to and press C-c w or select the refile action from the actions menu.
To refile multiple headings, run `helm-org-in-buffer-headings` or `helm-org-agenda-files-heading` and mark the headings you want to refile. Then select the heading you want to refile to (without marking it) and press C-c w or select the refile action from the actions menu.
Tags completion use `completing-read-multiple’, perhaps have a look at its docstring.
From an org heading hit C-c C-c which provide a "Tags" prompt, then hit TAB and RET if you want to enter an existing tag or write a new tag in prompt. At this point you end up with an entry in your prompt, if you enter RET, the entry is added as tag in your org header.
If you want to add more tag to your org header, add a separator after your tag and write a new tag or hit TAB to find another existing tag, and so on until you have all the tags you want e.g "foo,bar,baz" then press RET to finally add the tags to your org header.
Note:  A separator can be a comma, a colon i.e. [,:] or a space.