The threadscrew length is determined by your Z axis, the metric calculator can give you that number.
1 5/16-18 X 5 M8 X 130
12 5/16-18 X 2.5 M8 X 65
2 5/16-18 X 1.5 M8 X 40
28 5/16-18 X 1.25 M8 X 30
These are screws, you can either use 5/16-18 with the length in inches or the M8 with length in millimeters. So you need one screw 130mm long, 12 that are 65mm long, etc.
Same on the rest, 43 nuts for screws, a single special nut for the threadscrew (8M and longer than the normal nut). The M3 x 10 screws are for mounting the steppers and really do need to be that. If you can’t find M3.5 hardware you can likely use M3, but be prepared to add washers if the screw heads and nut size are close to the hole size. Structurally they have plenty of oomph.