dose i need more mf than 125 to find soj tal amu tal armor etc can ohm droping in nm cow chao?

Yes

You can find any of those items with zero MF, it's just less likely

200-300MF is usually a sweet spot, but depends on your build. Basically as much MF as possible without sacrificing kill speed. Kill speed > more MF.

Pretty sure NM cows cannot drop Ohm. Google Silospen drop calc