I will try to answer all the questions in one reply. Serging makes the seams too bulky and difficult to press to one side. Remember, you can't use steam, starch, or press from the front or your seams will show. Silk is notorious for spotting if dampened in any way. You also cannot use the high heat cotton requires. I would caution using any other fabric with silk because of the difference in heat required and moisture. I would suggest using 3/8" or 1/2" seams and using a pattern that calls for as little manipulation of the fabric as possible. The fewer the seams the better. But then it is your quilt, so do as you please. These are just my suggestions. Also, interfacing can be used but you have to use one that requires a low heat for fusion or it won't hold fast to the silk.