questions about analytics / targets sticthings

hello internet friends !

just some Q about analytics / target stitchings.  I have come to understand that this is accomplish via the SDID.  also it seems that SDID is fresh generated by hit (analytics, target or perhaps both).  

my Q is this...does the Visitor API initialziation  instantiate the SDID?  If so does it ultimately matter if/when/how the mbox calls are execute on the page in relation to SDID initialaizions?  also are the SDID sets 1:1 or many:many

are there any docuementations on this?