Or maybe he was smarter than yourself (no difficult task). Why would he need to "name the target" or "date the letter." HA HA HA. He is telling his wife what to do if he is arrested or killed. So now think real hard. What was Oswald doing at this time that might lead to his arrest or murder that night? Was his typing class that dangerous? Weak sauce.
I can't image this this normal, well adjusted person shown below would try and shoot a perceived "fascist".
Just to add, item #11 in the note that Marina found reads:
"If I am alive and taken prisoner, the city jail is at the end of the bridge we always used to cross when we went to town (the very beginning of town after the bridge)."
This is where we get the "So that proves he shot at Walker?" response. Besides, the photo is fake, right?