so, scaling the mesh should be pretty easy. If you select the mesh renderer you'll see a "ScaleField" property. This is empty by default, but you can type in the name of a float3 particle field storing a non-uniform scale for the mesh.
You can then add an evolve script that does something like this:
Scale = float3(1 - LifeRatio, 1, 1);
Here the scale along the 'x' axis will start at 1 and end at 0 when the particle is at the end of its life.
You can also plug a curve in there if you prefer:
Scale = float3(myCurve.sample(LifeRatio), 1, 1);
Regarding the UV scrolling thing, with v1 I don't see any reasonable solution really.
If your mesh looks like the video (mostly flat and stretched out?) you could probably get away with a ribbon instead, which will support scrolling through the "TextureUField" property
Otherwise, you can always use a custom material in the final game engine ? of course you won't get the proper preview in the popcorn editor itself. Which engine are you using?