You can set any property an object has to anything you want to that is a known quantity. 
So, angle that you asked about, possibly the easiest of all - 
Code: Select all
on mouseUp
   set the angle of widget "Icon" to the angle of widget "Icon" +90
   // rotates clock wise, use -90 to rotate counter clock wise
end mouseUp
Sizing up (the graphic is merely there to set a boundary), percentages would be done by multiplication, pixels would be by whatever integer you use for the number of pixels using addition - 
Code: Select all
on mouseUp
   if the width of widget "Icon" >= the width of graphic "Rectangle" then exit to top
   set the height of widget "Icon" to the height of widget "Icon" *1.5
   set the width of of widget "Icon" to the width of of widget "Icon" *1.5
end mouseUp
Sizing down, percentages would be done by division, pixels would be by whatever integer you use for the number of pixels using subtraction -
Code: Select all
on mouseUp
   set the height of widget "Icon" to the height of widget "Icon" /1.5
   set the width of of widget "Icon" to the width of of widget "Icon" /1.5
end mouseUp