You will not add mass unless you really up your calories while doing P90X. Considering you're planning on biking during the day and P90X in the evenings, you are definitely not going to add mass. You will be burning way too many calories for that, and unless you're eating 3000+ calories with that, you will absolutely be fine.
What you will add is exactly what you're looking for. Abs and legs. Not to mention more definition all around your body, but the one thing I'd say P90X works out the most is your legs. With all the squats, plyometrics, and yoga balances, your legs should improve big time.
I'm not sure, but from your post, it seems like you are looking for a schedule for your P90X workouts? Do you have the document that shows you when to do which workout? If you don't, I can send it to you. Either the classic or the lean option would work fine for you. I'd go for classic though, as you will have Plyometrics which should help a ton. You could also do the lean option and replace Cardio X with Plyo X, and you should be fine as well. The only other difference between lean and classic is the "Chest & Back" workout is replaced with "Core Synergistics." You can't go wrong either way.