The blue crayon marking is:
Precanceling postage due stamps with any provisional device is very common, in this case at Pittsburg, PA (no H, long tangent for another thread) in Allegheny county, PA. There is also an Allegheny in Allegheny county, but the post office clerks obviously knew to direct the H.J. Heinz mail properly.
Accounting: I don't recall the exact date, but at some point the UPU countries just kept their own postage due receipts as the exchange of money transferred was almost equal and took a lot of accounting expense to track it, etc. No doubt someone here can provide more precise particulars on the date.