Wallpaper and Wallcoverings - splitting the room in 1/2

Hi. Now I have some idea in how to remove a popcorn ceiling and to float a wall, I am ready for the next project. That room will be split in 2 halves, the bottom 1/2 will be a wall paper and the upper 1/2 will be painted with a boarder. Here is my question, what is the ideal highet to split a wall?. I am also affixing a base molding about 3" and another molding at the split(2-3").
One more question, do I have to take into consideration when primering and preparing the wall that wallpaper will be installed???
Thanx a million.

Hi bee40, The height to the top of your border is a matter of personal taste. I have some thoughts for you but in the end you need to pin it in place and look. On 8 foot ceilings the top edge is 32 inches from the floor.On 9 foot ceilings it may need to be moved up an inch or just slightly more. These are standard proportions and seem to yield a nice balance. If using flat wall paint, paint to well below the border level. If using egg or glossier draw a line around the room where the top edge of the border will be. Paint to 1/2 inch below this line.This will keep you from having to size or prime paint for the below paper. Hang below paper to center of border. Float the top edge of the below paper once or twice to keep this edge from showing through the new border. Sand and hang the border...Mike