It has a dust cap
Could be made up , as south america take there watch to a local watch maker . Many you watches in non OEM set up.
I dont know
Bezel is not correct , dial is later version, hands not ok . But this is hiw a barnfind looks like serviced over time with parts availiboe Added a picture of a original mk 1(mk2) l i have. Also side view Not an expert on speedmasters btw ...
An extract is really the only way to tell . . .
. . . if this is a barn find or a Frankenstein. If the movement matches the case, then you have the makings of a barn find. Bringing it up to spec might set you back more than its nominal acquisition cost. Lots of issues that need to be addressed. Art