How to paste yanked text to vim command-line

There is if you create a mapping, e.g..

:nmap , $p

Then you can type , to paste at the end of the line.

Remember, one way or another, you'd have to tell Vim that you want the text at the end of the line, and not where the cursor currently is; by default, Vim has no single key-stroke for this.

Yes:

:r !echo "foo"

See

:help :r!

That will insert the output of the command after the current line. If you want to capture the command output into a register that you can paste, you can do this:

:let @a = system('echo "foo"')

Now the output of the command (including the trailing newline) is in register a. See

:help let-@
:help system()