🚀 go-pugleaf

I'd like to purchase an external cd-rom to use between my 486dx-33 desktop
and my 386sx-25 laptop.  

A few questions i'd like to know the answers to before hand are:

[1] whats the difference betweena scsi and a parallel cd-rom?

    without knowing what the difference is i would opt for the parallel
    version so i would not have to fit both computers with a scsi card.

    are there benefits to a scsi cdrom over a parallel?

[2] with such bottom of the line computers would the speed(4X, or greater) 
    of the cdrom matter much one way or the other? 

[3] is there anything else of imporatnce that i should know?

thanks in advance, glynn