My 38 Super is a Colt Special Combat that I use as a carry piece occasionally. I load the 124 gr Golden Sabres at 1300'ps using HS-6 powder. That's a max load so work up to it. Because of the design of the GS bullet, you'll get a little more velocity out of them than a similar bullet weight due to less bullet drag. Terminal performance is as good as anything you'll buy.
Yes, you can use the .357 bullets providing you have the correct data to do so. There is more bullet drag therefore more pressure versus the correct diameter. I doubt you'll like the 158's out of a Super-just not enough velocity to make the bullet perform. I would expect velocities around 1050'ps max.
