Adding a pond, stream, columns, windows and granite.

[Katalyst777]

Columns are located in the Library Browser under Millwork and place and move like other objects.

I don't understand what type of problem you are having with placing windows in a wall behind where you want the columns. Could you attach some screenshots of what you are seeing?

Check out these online Help Database articles for your other two questions

Article Number 447: How to create a pond and stream

Article Number 71: How to change the color or material of a single wall