Re-Volt's file structures don't really change often, and it looks like that plugin was last updated just three months ago, so it should be as up-to-date as a plugin would need to be.
Many of the questions have been mostly answered, but here's a few extra things that haven't been mentioned yet:
1. From what I can see, the 3ds Max plugin is only an exporter. Unless there's a different way to convert RV's prm/m files to a format that 3ds likes, and if you want to stay in 3ds, then yes you'll need to make or find the models yourself. On that topic, though, not every detail in the world needs to be on the main mesh. This game is setup with what it calls "instances" which is basically something where you model a single bench and then tell it to duplicate that bench and place them down where you want them. (see the links in 3 for more on this) You can re-use the tree models (for one example) that the game already has. Maybe take a look at this, if you don't want the hassle of working around the existing mapping: http://revoltzone.net/tools/26435/Re-Vo ... l%20v1.2.2
3. As mentioned, you can use the in-game MakeItGood tools. These tools are used to define most of the stuff in your question and then some. Documentation for those can be found here
The .inf file, which contains things like the start positions, is detailed here.
4. I'm not entirely sure what you mean either, but you can look at existing tracks for examples. You can use up to ten different texture sheets. Faces connected to each other can be assigned to different texture sheets. The texture files have traditionally been 256x256 or 512x512, but dimensions in excess of 2048x2048 are possible too. You can use BMP, PNG, and many other formats for the image, but the filename has to end in ".bmp". The mapping doesn't do any tiling on its own, so you'll have to manage that. Along the same vein, vertex shading can be done as well.
5. With some of the effects this game has (the most problematic of them being the warping effect around a shockwave), it's probably better to keep things joined up. That way, you don't get holes like this
opening up in your track when one of them shoots through.
The track itself looks pretty good! Because of the tiling thing you'll probably want to subdivide some of those larger faces. Also because of the tiling (and also because of the way the game uses the mesh geometry to create effects such as a black smear left behind by explosions), you'll want to keep the mesh as regular as feasible.
It might be worth taking a second look at that bench-lined path, and see if you can make it any smoother around the edges. Details like that, or the lack thereof, stick out quite a bit when you're down low on it with a car that's a quarter of a meter tall. Don't be afraid to split the path down the middle to get more control over the geometry if you need to. Or alternately, maybe look into whatever equivalents to bezier curves 3ds Max might have.