Thanks for reply Franck,

For 8:
Yes, all piston engines needs to use "primer" before start. I understand the principle. But I am interested in how it was "practically" done in case of Bf 109 E.

I think that idle primer knob is in depressed position. Pilot needs to pull it first and than push it to inject one "dosage" of fuel into cylinders. The red colored sentence from original manual then probably means that pilot must be sure after finishing the work with primer knob that the knob is again in depressed position, ie. it not remain pulled (there is probably no spring inside button).

So correct loose translation of the last sentece from step 8 should probably be:
Be sure that after finishing priming the knob lie on the fastening nut, ie. stay in depressed position.

Beachte, daß nach Betätigung der Pumpe der Betätigungsknopf an der Führungsmutter anliegt.