Is my atmega2560 schematic correct?
for the basic function of uploading a sketch your board schematics is indeed correct and going to work. 
I can't say much on the PCB as what you have posted is a partial design, in particular it doesn't show the solder mask expansion and other details which might greatly influence the final result.

Please also note you don't need a reset button, a voltage regulator nor an external oscillator for the basic function of uploading a sketch, but I believe you also want to have the ability to run the sketch without the programmer being attached...