Generally 20g / day during loading (1 week), 5-10g a day for maintenance (5 weeks), then 2 weeks off in a 2 month period. 10g a day maintenance is debatable (5 might be enough) but it's relatively inexpensive, so personally I figure why not? If you want to do 5g/day for maintenance, that should be fine. You might want to break it up; some people report nausea from as little as 10g at a time, or even 5. I have an iron stomach and have had 20g at once with no problems though. Even if you don't lift a finger, the water retention will put 5 pounds on you, mostly in your muscle tissue, which will help appearance. It simply increases your endurance & short-term muscle strength, allowing for better workouts, which in turn build more muscle. Nothing unhealthy about it.
As far as lifting, make sure to use proper form and pick a weight that you can do 6-8 reps of before your muscles simply can't do another rep, and don't hurry the movement either. Bowflex and such machines are very weak in comparison to freeweights, which is the only equipment I'll touch, personally 🙂 You generally want to do at least 3-4 sets of each exercise, taking off weight on subsequent sets if necessary to stay in the 6-8 rep range (give or take; anything from 4-10 should build strength & mass). I get good results doing 8 sets but peoples' bodies, schedules, and motivation vary, so experiment & see what works for you.
Edit: just saw your last question; 1-2x per week for each muscle group is the norm; more than that and you're risking overtraining. Some elite bodybuilders do each muscle 3x a week. One grueling workout for each muscle group per week has worked out well for me; chest (bench & flyes), triceps (pushdowns or french press), and shoulders (military press) on Mondays, back (rows, pulldowns, deadlifts & shrugs) and curls on Wednesdays, and legs (squats, extensions, and leg-curls) on Fridays. I do 3 sets of everything except benches & curls, 8 each, and leg extensions, 5-6. The mindset I try to keep is to give it my all; I don't stop at a set, predetermined number of reps; I stop when I'm snarling and simply can't do another rep. I have trouble getting up the steps after my Friday workouts 😉