Multiple RTS problems

I'm building an RTS, and as it seems there aren't many doing the same.

First, my selection box works and selects the units properly. But my problem is that I want it to deselect the unit when the box is dragged off of it. So when you select four units and decide to only select two you can move your selection box off of two of them.

Next, my units move to the waypoint, which I set as the mouse position when you right-click, and then don't move to the next. I think they bunch around the point as a group and don't actually reach the point so they never advance to the next set waypoint.

Finally, I can't seem to devise a way to make them forget their previous waypoint that they are on their way to to so they can go to their newly set one.

A template would be very helpful, as the only one I can find doesn't help (the tank RTS).

EDIT: And here's my .cap to look at. It's hardly made any progress but at least you can see what I'm talking about.

http://filesmelt.com/dl/RTS.cap

Okay, I know how to make your units be unselectable. I just need to know which version of construct you are using. If you are using 0.99.85, then here's a cap that will show you how I made units selectable and unselectable.

http://www.box.net/shared/iejy4lon9s

I'm sorry, but I haven't gotten to making units stop at a waypoint and am trying to figure it out for myself as well.

By the way, don't create another unit until you have moved one unit of Team1 away from the spawn point. Also, read the comments to understand all the controls because I didn't use the same ones as you.