bodybuilding is an extreme activity. every aspect of it is extreme. the only way to find out what your limits are, is discovering that you've gone a little too far. once you understand your absolute limits, you can dial it back, just enough to walk that fine line and continue to always be striving for more. on or off cycle, i use at least 2 grams of protein per lb. often, i shoot for more. i use less science and go more by experience. i've found that so many things look good on paper, but don't line up with my experiences. at the end of the day, all i want is the best result i can get. so if something works, i go with it. 2g per lb is pretty genreal and thats what it's meant to be, general advice. its a starting point. everyone responds differently to nurtrients and it'd be impossible to say exactly what you need without trying it out and seeing how you respond. if you aren't comfortable with that, then start with less. start with 1.5 g per lb and go from there. 

4000 cals is really not that much food when it comes to bodybuilding. if you find yourself getting overly fat, dial back the carbs a little. maybe replace them with healthy fats. it's going to take some experimenting to see how you respond and its going to take time. after a solid year of working with your diet, you'll have a much better idea of what you need and how you respond. its a life long proess though. factors like age and muscle mass will effect the formula and it'll always need to be adjusted. what works today will most likely not work next year, but you'll have a much better handle on where you need to go from there. 

i would suggest weighing all your food, logging what you eat, using the mirror, progress photos, measuring tape, skinfold calipers and the scale to evaluate what is happening with your body. and make sure you give yourself enough time to see if the plan is working. i feel that it takes me about 6 wks to tell what direction i'm heading.