You are absolutely right. I'm not sure that his children actually feel a good education is unnecessary--they only follow the wishes of their father--but Bob Ewell places little value upon it. As the father of the family, it is his responsibility to see that his children attend school, but he only sends them on the first day of each year so they can be enrolled. According to Scout,
"... the truant lady gets 'em here 'cause she threatens them with the sheriff, but she gives up tryin' to hold 'em."
Bob has decided that since two members of the family--he and Mayella--can read and write,
... there was no need for the rest of them to learn.
As far as the importance of survival, the Ewell family takes advantage of every opportunity available. The roof of their house is made from smashed tin cans retrieved from the dump. The children scavenge the dump daily, making it tough for rats to find a crumb. They carry buckets of water from a local spring, since their house has no running water. They make shoes out of "strips of old tires", and Bob hunts out-of-season to put food on the table. Bob's survival skills are strong--he oftens spends several days at a time in the swamp--and he avoids detection when he prowls around at night. A different type of survival instinct kicks in after he beats his daughter, and Bob decides to blame it on Tom Robinson to deflect attention from himself.