That's a very nice Strat copy and fitted case, and I would say it's a Made in Japan build, complete with brass nut which is typical of the era.
Many late 70's and early 80's el Degas models came with Di Marzio super distortion humbuckers but I don't know if the single coils were also DM's. I'm sure they'll sound just fine.
As for the input jack housing, that's no problem to reverse it. The previous owner may have turned it around to avoid having the amp cable hang down. Tucking the cable behind the strap at the button makes it more secure from accidentally tripping over it and ripping out the connection while on stage.
Most players don't bother changing the input jack's orientation, but there's nothing wrong with doing it.
If the actual input jack appears to be missing, the retaining nut has likely worked its way loose and the assembly has simply fallen inside the cavity.
No problem. You can reassemble it when you take the housing off to reverse it. If it is in fact missing (unlikely) it's easy to solder a new one in place. No worries there either. I'd buy it!!
