You can place the 3ds by entering x, y, z coordinates in the Construction Kit by clicking this icon , or you can place it manually from the editor by Scenery>Choose Scene Object...
can you automatically rotate 3ds in CK to fit the track? Like for example if I wanted to strap magnetic fins onto an inclined hydraulic launch.. ie. TTD ? Fitting them in on the editor is nearly impossible lol..
rotate to track feature? like I have no idea what my incline angle is lol
To find the incline angle load the piece of track that is inclined into the AHG (so save it as a whole new track, or make sure it is the ending track piece on the coaster) and look at "Slope, Out".