I do believe this is correct for basic 501st approval. For MEPD deployment and SWAT, i would say that the overlap method build is not acceptable.
Jean-Sebastien, weathering is looking like your on a great start. I also went the acrylic way for weathering.
May i suggest use a damp cloth, mix some burnt umber and a black together, apply it to the damp cloth and dab the armor pieces lightly. This will help to dull the armor (still too white), thats what i did as a base coat on all the pieces before the detail work, with the lighter browns.