First just let me say ask thousands of questions, it's the only way you will ever learn.
1. It's .7 to 1 g per lb of LBM. Don't feed the fat bro. That's if you wanna maintain. Eat more if you want to bulk (eat big, lots of carbs too).
2. To get that nice V shape you need to make sure your waist is small and your shoulders are wide...then it really looks nice. Wide grip pulldowns for back width, or
wide grip pullups if you can do them. Do heavy chest work, thats about all I can tell you. Gotta be consistent and eat big to put muscle on, AND LIFT HEAVY. Don't be afraid of lifting heavy.
3. Middle of the back can be targetted by heavy reverse grip (palms facing you) close grip chinups'. Just like a pullup just turn your hands around so palms facing you and put the hands as close together as you can. If you can do actual chinups with bodyweight, then put a weight belt on and hang plates off you. Back should be vertical or real close to it when doing these.
4. Reverse Hypers, Cable Pull-Thrus, Heavy Good mornings will hit it. These are great, especially teh first 2. Deadlifts should be in your routine, or some variation of them. Rack pulls are another great lower back exercise.. Go heavy heavy heavy, this will make your back grow.
I got great videos for you if you don't know what reverse hyper extensions or cable pull thrus are. Also have good videos on deadlifts, good mornings, just about any big
compound movement a powerlifter would do lol.