always known doglegs just to be a name for shift pattern putting both 1st and reverse furthest left out the way. You never really use those 2 gears when driving fast, to get going shift up over and up into 2nd that pattern looks like a dogs hind leg. The dogleg clutch arrangement is what gives you clutchless upshifts just because box has dogleg pattern dont always mean it has dogleg clutch arrangement many Getrags dont. The dogleg clutch allows you to force the dogleg fork from 2nd to 3rd then 4th to 5th.

Normal gears are helical think of it as taper on each spline helps mesh the gears together smoothly whereas straight cut more sensitive to difference in engine to road speeds. If eithers stronger depends what way? on helical the spline tips wear out but less likely too because they guide the mesh, opposite to straight cut they are stronger but get road to rpm speed very wrong more chance splines immediate breaking. Straight cut with slight taper on thrust side known as semi-helical.

hope that helps