After 14 years of being able to mill my grain at Listermann's homebrew shop in Cincinnati, which was a couple miles from my house, now it's my turn to join the ugly junk corona mills as they closed

Got a Victoria mill for $35 on Amazon and installed it in a bucket just like above. Of course when I measured the 2x4", I didn't take into account the fact that a bucket narrows as you do down. Doh! A couple cuts later and it fit.
Was planning on manually doing the first batch but found a bolt that fits so I'll use my corded drill.
Now I just need to figure a better hopper. I found the ones used above but damn they are pricey. If anyone has any recommendations let me know.
Also, what do you recommend to do if anything before I run the grains through it for my next batch? Should I run some grains through and toss them out? Is there much risk of getting metal shavings? I feel like it's not a huge risk since I BIAB and that should catch most and if not, they would settle out in the keg I ferment in and serve from and I use top draw pickup tubes.
Also any tips for setting the gap? I saw online someone said, "For BIAB, tighten it all the way down, and back off slightly." Is that the best method? Thanks!