edit the plane and erase some faces. It was just an example but there are many method to avoid problem of holes.I am sure this is a stupid question but how do you get the holes in the plane then? I really don't get that...
Specialized software saves time, but if it is to move from one software to another, this can be longer. It depends on the complexity of the work involved. For simple things it is better to stay on the same software. for complex things, the use of several software is useful. I prefer to stay in truespace as possible but i find Rayman is right too. We are different. The problem is knowing what software you really want to use and you can't know that before try sketchup or other soft. Then you will know what to do. As Rayman said, you lose time to learn but you win time for futur project.