Sewing silk velvet can be a beast. The one garment that has been in my winter/holiday wardrobe for the past 30 years (in various iterations), is a pair of silk velvet pants, usually black. Take a look at the video to see the easy technique for pleating. I love these soft loose fitting pants; they are comfortable, warm in the cold, cool in an overheated house, I can cook in them, sit on the floor, wear them to a casual family gathering or to an evening event. The pant I am using now I got from Eileen Fisher a few years ago, but you could easily make them. The secret is to allow a bit of extra ease in the pant as the pleating takes up some space, and you want the pant to hang with fluidity.
On Vogue 9193, I'd eliminate the drop pocket and make the yoke from a soft knit.
Vogue 8499 is has a full cut, do a tissue fitting and/or, make a pre-test to be sure the silhouette is right for you. If the pant is too full, you could go down a size or take it in at the back leg seam.
Vogue 9228 with a soft line and origami hem detail is another design that could take well to pleating.