Sky couch works like this. There is a section on the plane that are 'skycouch configured'. They are a bank of 3 seats on either side of the plane in the first section of economy. If there are 3 of you in the seats you pay a nominal fee to be in that section and get a matress protector pad, and some big pillows and the ability to have a footrest and in seat charging that is not offered in all section of the plane. The arm rests also fully raise up which I am told they do not do in all of economy.
If there are two of you, you purchase 1 seat and then share the 3 seats. As I said previously at 5ft 1 inches long and 79 cm wide (and less if the person in front reclines) there is no way you could both lie down. The best you would do is just have more space. My husband at 5ft 11 was able to sleep very happily in the sky couch but we purchased the 2 extra seats for him. The two boys 12 and 14 (5ft) shared 3 seats and myself and my daughter (5ft and 5ft 4) shared one. We found it difficult to get comfy to sleep lying down and we aren't huge. It really isn't for two adults or even one and a kid over 4ft to enjoy sleeping lying down. But it does work for just giving you more space, a footrest, arm rests that go up and in seat universal power charging. I wouldn't worry about econmy food and tv as it is all good in econony and you can order drinks and snacks from the TV when the meal service is not happening so that is a bit of fun. Though on the 747 400 as the seats recline quite well it is a bit difficult watching TV when the person in front reclines, and the TV doesn't angle up that well. Might be a problem for you being so tall. The boy next to me was about your height and he just looked absurd sitting in the economy seat on that plane. The aisles are also super narrow as it is a 3, 4, 3 configuration so there is no sticking you feet into the aisle to get more comfy. There are some seats up the back of the plane that are a 2 seat config and that gets you off the aisle, I think you have to pay more to book them as preferred seating and not sure if you are guaranteed them.