1.)Contrary to previous posts, whether you're a veteran in the gym or not, you should never be in the gym for more than an hour. In lamen's terms, after an hour your body will start eating your muscles for fuel. The only people who jet past an hour are either on the sauce or trying to lose weight. A general guideline is roughly 45 minutes.
2.)You've only just begun the process. Again, contrary to previous posts, work one muscle a day with the exception of biceps being paired with triceps. I've been weightlifting for years, and I still only do one muscle group a day. Especially since you're new, it's always better to focus on 1 bodypart per day, learning the mechanics and what weight to use for each individual exercise. When and if you feel you want to try pairing muscles together, I'd recommend grouping a push/pull. (ie. chest
3.)The sticky I made on targeting muscles will be helpful. Most of the exercises are pretty easy to figure out (pullups, shoulder press, ect.) More often than not, your best teacher is the people in the gym. Watch what they do. Watching them execute a certain exercise you'll be able to see what it's targeting. Usually the biggest guys in the gym will be the most helpful.
4.)High reps and low weight will tone your muscles, only diet will define them. High weight and low reps will both increase your mass and strength. But, for you I'd recommend a rep range of 8-12 only because your muscles need to get used to the stress of lifting weights. The more lactic acid that builds up from high reps will help strengthen your joints for the future. Once you've developed the routine you like, and been making steady progress in the gym, that's when you start lowering the rep range so you can handle heavier loads.
*Honestly, the first year and a half you'll experience the fastest gains of your life no matter what routine you do. As long as you're spending equal and ample time on each muscle and eating your body weight in protein you'll grow.