I am planning on using the Pfitz plan as well. 24 weeks, 70+ miles. Goal marathon is Chicago. I started doing my base training Jan 1 and am up to about 80 miles/week. I will stay around there until I start the program.
The vo2max sessions total 8 workouts and are part of the mileage for that day (ie, 9 miles for the session, 11 miles, etc). I plan on doing half the mileage as a warm up, run the vo2max workouts, then run the second half of the day's mileage as a cool down. That could help to limit injury, as well as giving yourself more than one day of rest from your long run before doing the vo2max workouts. So those would be my suggestions.
The vo2max distance varies from 600m to 1600m, but most of them are 600s. There isn't much speedwork outside of these workouts. Striders every week and some tune-up races but most of the workouts seem to be geared to aerobic strength and endurance.