Now for the grid... I did the following thing... First I made a new doc bigger than my working doc(2000*1500)...
Also I wanted like 100 grids... Made an another doc of size 20*20 px... I stoked the whole image(20*20) using the layer fx with a 2 px size black with the center position... Then I defined a pattern...
Now back to the big document... Went to channel, made a new channel(named it grid) and filled with the pattern...
Now going back to layer and making a new layer... Now selecting load selection and loading the grid channel...
Select inverse and fill with the color used for grid( in this case #c8c8c1)... Now the grid is ready...
Transferring the grid to my avocado doc... Using perspective( via transform) I get this...