In my opinion and my experience "active recovery" is a bullshit. This is one of this thing that seems to be logical on paper but fails in real life. Yeah, geting this blood flow, making sure all the nutrients are pushed to the growing muscles. If this would work then after a heavy squat workout you should be doing 3 sets of 50 air squats every 3 hours.
Long story short - if you want to focus on running marathon than 2 days a week of lifting weights will drive your strength up. It is not optimal but you want, at least for now, focus on runing. Do the program as it is. Do the bench press if you dont have injury. Benching with good form will not fuckup your shoulder. Read the book to learn how to do it. After your marathon you will make your weightlifting priority.
The most important thing - you need to eat more. Not just for lifting but simply to stay alife and healthy. No men should eat less then 2000 kcal. Simply because a juicy cheesburger with becon and fries got more then 2000 kcal. And why would you not want to eat something like that every day until you die ?