I don't use Easel, so I can not explain why it uses the port it does. But PicSender only uses the com port numbers as assigned by Windows.
The error you get when trying to home can be found on PicSender's GRBL screen (click the GRBL button). Error 5 is 'Homing cycle is not enabled via settings". To enable homing, set grbl's $22=1 (see page 19 of PicSender's tutorial - click 'Help' then click 'Tutorial').