Firstly, Sec 4.1 of the MS-00193 applies to the raw material sheets alone and should not be applied to the bulkhead assembly or any other component for that matter. Regarding your 2 questions, these are more related to design and structural integrity. Unfortunately, I cannot help answer these questions. I checked the drawing and there seems to be no specific mention of the weld line orientation. Please check with Harris Blake who released the drawing on your questions. Thanks.