Yes they can do whatever you need done.
Yes .
They can swap the sights on glocks to anything you need.
I imagine the answer depends on why you can't see the front sight. A smith can move them or swap out the sights with taller sights, but the front sight should be visible now if the weapon's barrell (and therefore the sights mounted on it) is oriented with your line of sight. Can you say more about what is actually preventing you from seeing the front sight?
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