Yes you get the exile trigger when you copy duplicant because duplicant is not really a clone effect. It is still the same card with a small addition of a creature type. When something is about to enter the battlefield "as sculpting steel enters the battlefield" it happens before the enter the battlefield triggers because it is a part of the resolve to put it into play. Then enter the battlefield triggers will happen
And no, progenitus is not targetable by duplicant. Because progenitus has protection from everything
Protection from everything means four things (we often use the acronym DEBT to help remember the 4 parts of Protection):
All Damage that would be dealt to Progenitus is prevented;
Nothing can enchant or equip Progenitus;
Progenitus can't be blocked;
Progenitus cannot be the target of spells or abilities.
Protection from [color or quality] means those same four things, except that you add "by things with that color or quality". In the case of Progenitus, nothing at all can do any of these four things to it. Since Duplicant's ability targets, it cannot target Progenitus.
I'm a lvl 1 judge, but that doesn't make my answers more valid than those of people who aren't judges. What matters is we can quote the rules to back up our answers. When in doubt, ask for such quotes.