I do not try to combine gaining and leaning at the same time. So when I am gaining I do very little to non existent cardio because it steals needed energy from my lifts. When I am leaning I do low impact cardio 3 to 4 times a week. My way is not for everyone because some people like to stay ripped up all year long, but I dont, especially when I am trying to mass up. I eat my meals clean all of the time regardless of what my goal is. I only change two diet things when I am gaining. 1. I have ice cream or pie filling before bed (sounds crazy, but my mentor who had some serious cred as a old school IFBB pro introduced that to me) 2. I mix up a weight gainer and set an alarm in the middle of the night to wake me up to drink it.
As for workouts, they are intense, usually around 1 to 1.5 hours. HEAVY WEIGHT as in 400+ benching, 600+ squatting and deads when I am gaining. Obviously I go lighter and more reps when leaning out.
The most important thing I can tell you is that you will respond to different things in different ways, so you really need to experiment with what you respond to. Keep accurate logs if you need help keeping stuff in your head to compare and take lots of pictures as you are trying different things. Your mind can trick you, but good pictures will tell the truth. Do the same poses each time, use the same camera each time, take them in the same place each time, and if you are interested in comparing a specific body part make sure you get pictures that are apples to apples, dont decide you are going to compare your delts in a picture that you just trained delts with to a picture that you didnt just train delts in.
Good luck!