There were some issues with the Height Map, but eventually things fell into place and this is what I've ended up with:
In order for the play not to fall through the terrain model, the model has to have collision. If I would have imported the land from 3DSMax, I would have had to set up a collision mesh as well, which is extra work. The "Landscape" tool creates amazing collision when you generate a terrain through it via a HeightMap. As seen in the video, the player doesn't bump into invisible walls nor does he/she fall through the model.
The only collision issues are with the placeholder houses, but that's all right for now.
Everything seems to be in order for me to move on with the modeling stage and start looking at some architectural reference.