Why it cost so many forma?
To maximize the build, of course.

How the build works?
Start by killing enemies slowly till you stacked all galvanized mods and primary merciless, when you reach full stack, have fun killing!
-galvanized aptitude provide you maximum status chance and extra damage.
-galvanized chamber provide you extra multishots, allowing you to apply more status to enemy.

Is it steel path capable?
Yes, of course. The status is maximized.

This weapon lack ammo/arrows, what do i do after used all arrows?
The Arrow Mutation should be able to keep your arrows supplied.

Why not to build both crit and status?
As you can see, the crit chance of this weapon is only 7%, which makes it incapable on dealing critical hits.

Why is the grammar broken?
I am not an English major, sorry.