Game programming question

I started to program an isometric game, like age of empire, or red alert. I have some problems with the code…

  • I dun know how to figure the code that drags the building over “tiles”.

  • I can’t figure out how for an unit can find it’s path when there are obstacles

  • How can i select a bunch of units when I draw a rectangle around them

  • How can units get in positions like “square” or “rectangle”

If some of you can help me, that would be nice