1) Everyone has a maintenance level of calories they need each day in order to maintain the same weight (duh). You can overshoot/undershoot that number by as little or as much as you want. If you want to gain weight slowly you are going to have to start a quite strict meal plan. I would estimate that you should start around 3000-3200 cals. Track your weight for 1-2 weeks while you follow the diet CONSISTENTLY. If you are not gaining weight at the rate you want then bump it up by 100-200 cals. If you are gaining too fast then cut it back. It's a simple concept, really. The key is staying consistent day in and day out with your eating, sleeping, and training.

2) I would say a push 4day split could work for you if you're focusing on the big compound movements.

IW