Snowman,
Im a Division III fullback. I’ll tell you right now, the first thing you need to focus on strengthening is your low back, glutes and hams (posterior chain). This should definitely make you stronger, more powerful and more explosive. Do lifts such as good mornings, box squats (I think BFS uses these), DLs, sumo DLs, snatch grip DLs, glute ham raises, reverse hypers, cable pull throughs, etc. Also, focus on compound movements rather than isolation lifts. For example, do pushing movements and pulling movements, or rowing. Things like arm curls and leg extensions wont really help you in terms of football, so don’t waste your time with these.
Keep up your sprinting and agilities at least 2x per week. Be careful with the volume on the plyos.
Of course, the oly lifts are a mainstay in a football program however, remember that you cannot be explosive without first being strong. Work on building as much strength as possible here early in the offseason and use the oly lifts on speed days (work on bar speed!!!) Then, as the season approaches, increase the intensity of the oly lifts.
You can look into the Westside style of training as Landon pointed you towards and you should also look at EVERYTHING that Coach Thibaudeau has posted on this forum. He knows a GREAT DEAL about training athletes.
As for books that deal with football training, I think the two best books that I can think of are:
1)Coach Thibaudeau’s book
2)Joe Kenn’s (ASU strength coach) book
The bottom line, expand your knowledge in the world of strength and conditioning. There are different avenues to take, some good and some bad. The more you know, the better you will be able to find what type of training benefits you, as all athletes are different in some aspects.
Good luck to you, athlete.