My take (in a nutshell) is that she is a master program for the consciousness and that her body is just physical - but not important.
She can come and go from anyplace in the collective she wants because she is everywhere simultaneously and possibly a body is just grown for her (in a maturation chamber) for her to physically inhabit as required.
'If the Apocalypse starts, beep me!' - Buffy Summers
'The sky's the limit.....' Jean-Luc Picard, 'All Good Things'
courtesy of Saquist