Any question answered...

Lube everything and torque the bolts to 40Nm (with a torque wrench - don't guess)

Chainline should be 42.5mm when it's all assembled properly. The other place where there is scope for a small amount of error is that the BB face might not be exactly 34mm from the seat tube centreline. For that matter, your track ends/dropouts might not be symmetrically disposed about the centreline plane of the frame, so getting the chainring exactly 42.5mm from the centre of the BB shell and the sprocket 42.5mm from the midpoint between the track ends still might not get the chain ring and sprocket centrelines precisely coplanar.

Right, next tool on the list will be a torque wrench.

Although i greased and tightened it and it's now 43mm so I'll settle with that for now :)

Tbh i've converted an old concorde frame with 126mm spacing so there's going to be some discrepancies with that setup