How much surplus calories do I need to put on muscle?

Those free weights are probably good for you for single leg work like lunges and Bulgarians, and for arms and shoulders. I expect they're too light to tax you for squats, Romanians, or rows or presses. However, the Bowflex presumably lets you do various rows, pulldowns and presses, and will allow you to overload with more reps then more resistance week to week.

When I said 3-4 workouts, the thinking is it's a lot of volume to fit in 2 workouts per week. Typically that would mean 3-4 different days, but maybe you could do twice in one day if that suits your schedule, like focus on legs in one workout, and upper body in the other workout on the same day, something like that.