I'd just do them like shown.
Interface inside the sleeves (and perhaps stitch edges) for stability and cut slits and put the black part through like shown.
For the ones that aren't a completely different kind of fabric, I would just hand-sew them on where they need to go. You could do it with machine, too, of course - but for the little thin ones I feel doing it by hand is actually easier. You might be able to glue them, but I've had glue just rip off the top layer of leather before and feel like careful, neat, sewing would look equally good and be more secure.
The one of the sleeve looks like a zipper, so if your jacket doesn't have a pocket you could add one and use a black zipper and leave it exposed as shown.
If you bought a leather jacket, I'd be inclined to use black leather for the stripes - plus it's easy to work with in some ways. The "hard" part about leather is that once you put a hole in it, it's not really going away (fillers work to varying degrees of success and shouldn't be counted upon) - the good thing is that you don't need to fold your edges under or otherwise finish them - they're not going to unravel.
Disclaimer : This post written by a Grumpy Old Man
Actually in the pipes:
- Remaking Ser Loras doublet.
- Luke Skywalker, A New Hope
- Wind Waker starter costume in swim material
Eventually: Paul from Dune, Faramir, Harry Sullivan