What out of the ordinary things happen to three Maycomb citizens by the middle of October?

You can find the answer to this question in Chapter
27. 

#1: Bob Ewell got and lost a job with the WPA--all
within a few days.  Scout narrates that "he was the only man I ever heard of who was
fired from the WPA for laziness.  After this, citizens of Maycomb soon forgot about Bob,
but he tried to stirr up trouble once more by accusing Atticus of "getting" his
job.

#2: Someone tried to break into Judge Taylor's house
while he was home on a Sunday night.  He heard a scratching at the door, and by the time
he got there, the screen door was swinging open and a shadowy figure came into his
view.  (We can assume this intruder was Bob Ewell.)

#3:
Link Deas created a job for Helen Robinson.  To get to this job, Helen had to walk a
mile out of the way so she could avoid passing by the Ewell residence, because each time
she passed them, they "chunked at her."  So, Link Deas threatened Bob Ewell that he must
never speak to Helen again--then he spat on the ground and
left.