For horns you need to check on the DLS, download, and try them by opening them for edit and listening to the .wav sound file in your sound player.
For street running, there are many ways to do this. I've done it myself for some trolley (tram) lines and for some freight tracks in and around some factories, mill complexes, and docks. This can be both a pain and rewarding due to the traffic and the type of road and track combination. The roads have to be thick enough so the rails don't stick up too high which looks weird. There are road/track splines already available that are awesome enough to use, but make sure it blends well with your own roads. These are meant for trams/trolleys and may have wires attached to them, which may or may not be something you want. Having said this, I make my own.
The other issue is the roads need to not have traffic, or at least where the track is, so you need to modify the road so there is no traffic, and or create/use one-way roads on either side. I have done the latter for a transit system. I used a modified YARN road with a sidewalk on a single side to have one-way traffic. I then put the track in a middle on a grassy median strip with occasional crossings between. The ATLS crossings can be used, as you've noted, for blocking the traffic off. I did this for a sections where the track runs from the middle of the road to its own private ROW. It's a bit tricky to setup because of the long crossing, but it does work well.
Sometimes there are areas where you don't need traffic, but want to setup the tracks down the road. For such areas, use the thick roads and guiderail track, but modify a road to have no traffic. I've done this in many places, and only use static cars and trucks. Keep in mind though if you attach a no-carz road to an active road, you'll have carz running down the no-carz section. I avoid this by keep the road close, but not attached to the active roads.
With my mill yard and complex, I again modified an old 4-lane YARN road by removing the traffic and reskinning the surface texture with some cobblestones. These wide, thick cobblestone areas work for both the track to embed in and as a base for the various buildings to sit on. When I then place other objects, such as static trucks, cars, crates, and other objects, I then adjust their height above the ground so they're not buried into the pavement.
Now the track type can be a bit tricky. Technically you need track with a guide rail attached. I found that the SAM Tram Track (It maybe not called this, but its by the create samplaire), to be quite suitable because it has the correct profile for street running with the guiderails, and it's a great looking track anyway. When place through the road spline, the rails stick up just enough to look as though they are embedded in the road.
John