As you had understand from your experience and the previous posts, this funny plug is not an euro continental one, but rather a totally proprietary 12V plug (should I say a "meoptian" (meoptanian ?) one ), designed precisely for *NOT* fitting it in a wall socket...
I see increasingly on the second hand market Opemus enlargers with Meograde or Color 3 heads without there dedicated heavy "Trafo" transformers, so beware !
For the bulbs, you're not tied to a photographic reseller for finding them, any industrial or specialized lamp retailer can have it. These lamps are used in some video projectors and nightclub spotlights.
A reference you can use :
OSRAM XENOPHOT 64627 12V 100W Halogen
There is other references in other brands, I can find them for you if interested.
I bought recently two of them, brand new, on the *Bay for less than 6 euros...
Welcome to the Meopta Opemus user club !