I see. You could also have a quick glance at the sticking and off you go. The sticking is the same on all those websites ;-)
Yes. There's no other way if the tempo is slow enough as it would be hard if not impossible to control the rebound enough to make the strokes even in volume and rhythm. At 'medium' tempo (which may vary, depending on the drummer) you can keep up the wrist strokes or start incorporating rebound. But in the sense of 'controlling' rebound (with a controlled 2nd stroke on the doubles), not depending on it (on doubles, the 2nd stroke would be a bit weaker than the 1st stroke). That's the typical way to do it. Some drummers prefer to use as little rebound as possible and would get stickings up to crazy speed, without bounce/rebound or using just enough to make it work. From an ergonomic standpoint, go the (controlled) rebound route.Some can get it up to crazy speed. Don't stress yourself. Get your doubles clean. Do you have good/fast doubles? Just take those doubles and incorporate them into the paradiddle. Basically it's the same motion but in a different sticking environment.
If you have good/controlled rebound on the doubles, try working your 'single' doubles up. Choose a tempo that would be slow enough to play the doubles as single wrist strokes and work on it. You should get the speed up a notch or two. Also keep up playing doubles as controlled bounce - which is way easier to most drummers.