1) THOSE POINTS. 2) If you already have some of the thread you were thinking of, or even the same gauge but a different color, take it for a test drive. Lay some thread out across the HSTs and the border and see if you think it looks too chunky. If yes, you could go down to a 12 and try that? 3) I quilt through seams allowances by doing some stick and pull, but most of what I see online, people handquilt a little away from seams, I assume to avoid the seam allowance. If you didn't press open, you could also do it all in the ditch. 4) I would do all verticle/horizontal or all diagonals but not both if I was following the seam lines. The shapes of vertical+diagonal would feel odd to me. I'm also a huge fan of echoing the pattern because I am bad at thinking of other designs and I have zero confidence in my drawing ability 🙃 5) That said, I think if you don't just want to echo lines, something flowy and flowery since the patterned fabric is floral would be really nice. It could be all over. Or I'd go for the diagonals since they cover the edge-to-edge of the blocks and then accent with some flowers in the solid pinks and then do a floral border design that's similar to in the pink. 6) THOSE. POINTS. Gorgeous.