You need to mark the slit site which will be inside the natural fold of the dress as worn. Stitching Finds indicate running or back stitch for seams, stitch length 2-3mm. Unfortunately not many modern wools are fulled, and linen always needs seam finishing. French seams are a good way and evidence supports their use. Hemming is again by running stitch on a single fold or by a double fold help by a catch stitch .
Men Here is an illustration of a similar garment for men.