How long should a workout take in general, if i'm going to target a couple of muscle groups 3 days a week. How many muscle groups should you work and are there common groups to work together like Chest and Triceps or something like that.

Thrice a week splits generally take longer per workout due to the amount of sets you'll be doing during any given workout (as you'll be working more body parts on any given day than say...someone who does a 4 day split).

As a Max-OT advocate, I keep my workouts between 30-45 minutes (much closer to 45, though). In general, anything over and hour is running long (unless you're on gear and no one here should be).

No more then an hr for the weight lifting portion. Any longer then that is a sign that you're not lifting hard enough. Quality over quantity

*edit I should really use spell check before I post