Panel questions
First of all, I can't parent the brush with the panel. I have made func_brush, which I parented to panel (prop_dynamic) in object properties and with setParentMaintainOffset command.
Secondly, how can I define the amount of movement of the panel? I want it sticking a little, not fully extended out of wall.
What panel attachment point are you adding as your parameter? Different panel models have different attachment points.
TopHattWaffle has a solid video tutorial up that walks through it step by step if you're having trouble with the VDC Article.
The 'amount of movement' is entirely dependent on the animation you set for the prop_dynamic. The 64x64 panels have literally hundreds of animations. It can be a bit overwhelming but unless you're planning on doing something really nuts you should be find a suitable animation for what you're trying to do.
One additional thing that you can do if you need the panel to move horizontal/vertically before the animation itself starts is to Parent it to a func_movelinear (or func_door) and trigger that to open/close prior to the animation.