summer pruning of stone fruit

I have 3 semi-dwarf trees peach, pluot and nectarine, spaced about 2 3/4 feet apart. They are 1-2 years old and the lateral branches are going into each other. I am not sure how to prune these but I know summer is a good time to control height and I believe this lateral crowding can be done at this time also. But how? I do have a Santa Rosa plum for pollination of the pluot but that is about 50 ft. away. Will pollination still occur?

I live in zone 21 of San Diego. Thank you.