ONE
Yes, you can use straight stitch. Many folks believe you can’t since a straight stitch doesn’t stretch (even if using polyester thread) and the fabric does. Generally speaking, I use a straight stitch on stretch fabrics when one, it’s a vertical seam or two, it’s a seam with a short length. Why? Because your body and the garments you wear need to stretch width-wise for breathing, moving around and such. Unless you’re doing jumping jacks all day long, the seam/stitches don’t need to stretch up and down. When using a straight stitch, I have found that a shorter stitch length functions as well as looks cleaner.
TWO
For horizontal seams, use a zigzag stitch and wash-away stabilizer underneath so that you aren’t stitch through air and the feed dogs have something to grab onto. Tissue paper is another option for a stabilizer, but I’ve always had trouble tearing it away. Maybe it’s me, maybe it’s the paper. I like to blame the latter ;)
THREE
Have you ever tried to sew leather to chiffon? In most cases, the two together are like oil and vinegar. They don’t mix well. When it comes to mesh, pair your trimmings to the fabric. Don’t use a firm band elastic on mesh. That kind of elastic will tell the fabric who’s boss. For meshes or any lightweight stretch fabric/lace, try to use a soft elastic. It will prevent waviness and look better.
