One question...

Theme: Symbol, component in schematic

Can I define the assembly side for the component already in the schematic?
No, it is not yet possible to specify in the schematic whether a component is to be assembled on the top side or on the bottom side.

If you use the autoplacer in the layout view later, you can define where the packages (SMDs or wired) shall be assembled. You can also specify the side when importing individual packages.

If a package is placed on the wrong side, simply mirror it in the layout by using the keyboard key [m]. TARGET knows that you can't buy mirrored components and thus flips them to the other side of the board.