1.
"enable black mask" works just fine in "map initialization".
2.
Personally, I'd never play a map with a turned off minimap.
Fortunately, it can't be done.
Sorry.
If you're really desperate about it, turn off the "show on minimap",
so only the terrain will be visible...
For doodads and destructtibles, that would be "art - minimap - show" = false,
for units, "stats - hide minimap display" = true.
(Still, it's a pain to do, and it isn't very user friendly...)