Hi all, sorry for my ugly english. After uploading the sketch into the board is possible to use only atmega328 to save space on my custom shield? I need only a 16mhz cristal and 5V or I should put something else (resistor, capacitor, and so on)? Thanks.
Yes you can do that. The minimum you need is the three pin resonator with power and ground (analog and digital), decoupling capacitors, and reset tied to+5 through a resistor.
Search here for standalone atmeha or similar topics in development.