1) There is a direction associated with the regulator, If you look closely at one there's a arrow. Everything below that will be the regulated pressure. Everything before the first regulator is referred to as the high side.
2)No Limit except for space and cost considerations. Yes you can put tanks after the regulator but usually not done.
3) You can use a latch system to store the energy. I think what will work for you will depend on more information.
4) you can use various fittings from brass Ts to plastic quick disconnect T's. You may screw in
quick disconnect fittings into them.
30 Pounds should be sufficient for a pneumatic system. The old compressor weights in around 10 lbs.
You can use the rotational cylinder.