Not trying to sell you anything. But, the rain blocks in that pack would do what you wish, I believe. For a 5-second video at 28-32 frames per second, you would have to duplicate whichever rain block seems appropriate. Then stack them together into a very long (tall) object. Then just group them or wield them together into a single object. And then just animate that single object in a simple linear trajectory in the direction of your POV. (That is, drop the long rain block away and downward from your camera and down toward the ground.)

The rain blocks include lots of individual droplets, but also tiny little streaks to help convey the direction of the rain. Should work just fine - be pretty easy, I would think. Rendering times willbe a bit high because of the multitude of reflective objects, of course. But should not be too bad.

The lightening flashes should not be a problem either. Essentially, you are asking to turn on and turn off one or more strong "directional" lights. If it were me, I'd write a simple Python script to do this, or ask someone else on the C3D Python Forum to write one for me. Not a huge programming chore - just mostly a matter of getting the frequency and the duration of "on lights" worked out to your satisfaction. One advantage of "lightening flashes" is that you don't need any or very much gradual build-up of light and gradual decline. I think "on" and "off" should work pretty well.

I honestly cannot remember if lights can be animated in Vue as well, but that might be possible too, and then you would not need a Python script. Or, if they cannot be animated in the on and off sense and your version of Vue doesn't support Phython, they certainly can be animated to rotate in a circle. What you do then is to position a dead black cube in such a way that it is near the axis of the directional light and on the backside of the light when it points toward your scene. Rotate the light in a circle, so that it passes inside the cube for "off" and then continues rotating outside the cube and onto your scene for "on." I'm away from my computer for awhile, so I am just thinking this up, and don't know if actually would work. But you certainly can give it a "go," and when I can, I'll try it.