For Academy grads, what are the details of the GI Bill? Does it only begin to accrue after the initial commitment? When can it be used? Etc

For the Post 9-11 GI Bill it accrues after your initial 5 year commitment. You'll have 100% of the benefit at year 8 of active duty. The Yellow Ribbon program is a great one to research and I would also recommend looking into the Pat Tilman Scholarship program for your academic pursuits. Getting access to the GI Bill was pretty painless- I just filled out an application at on the MyBenefits page and I got a letter 6 weeks later about my eligibility and available percentage. Good luck and hope this helps!!

I was told that we didn't get the GI bill when I entered the Academy in '78 because our schooling was paid for. I don't recall seeing a deduction in my pay (back in those days the GI had to contribute like $110/month) either as a Cadet -- like the football tickets, books, haircuts, etc. -- nor after commissioning. Hmmmmm

That is a good question CPT (Join to see). The GI Bill I first enlisted under was the Vietnam Era GI bill. During my time as a cadet at USMA that GI Bill was still in effect. However that bill had an expiration date associated with it for the service members covered by it. In those days, the GI bill could be used while serving in the military and after separation there was a 10 year period during which dependents and spouses could use GI Bill benefits.
Hopefully the modern GI Bill's has similar provisions.