Merci, artie, for all the input.
My frustrated quandary may have reached a resolution: a colleague advises that he can provide me with a USB stick containing the whole megillah of El Capitan.
The only thing I will have to do post-installation is to separately download and install all the system and security updates associated with same. With regard to that, can anyone provide a list of the various updates I should install? And is there anything I should look out for? (Apple's El Capitan info is a tad confusing when I look at it.)
