This build focuses on Kohm's strength - namely, the inherent 2 bullets it fires at once after the initial spin-up. Because each of these 2 bullets gets a multishot proc (2.8 with this build), you fire between 4 and 6 bullets for each shot fired. Note that the 2 bullets per shot implicit does consume 2 ammo, not 1.

Due to this inherent mechanic, increasing status chance is not necessary, as the 75% base applies to each bullet separately. On a shot that fires 6 bullets, 4 or 5 of them will proc statuses. Status damage itself is dependent on the base damage of whichever element proc'd it, and in this case, increasing base damage yields more DPS than increasing status chance.

[Vigilante Supplies] is not necessary if you use [Carrier] for ammo conversion. If you use [Carrier], you can leave the exilus slot blank to use less forma on the other slots. However, I would recommend using [Vigilante Supplies] for the "chance to enhance crits", if you don't mind spending the forma.