Work order: Packet roller slide - energy efficient and secured

You should develop the control circuit for a roller slide. Special emphasis should be placed on safety and energy efficiency.
Requirement 1: The lifting cylinder is to hold in the current position even in case of a power failure, that means sagging down should be prevented. Give two possible solutions and discuss the advantages and disadvantages.
Requirement 2: The extension and retraction of the lifting cylinder should be throttled and this should be as energy efficient as possible.

Pneumatic circuit - throttles and check valves unlockable

Pneumatic circuit - throttles and check valves unlockable

Analyse of the pneumatic diagram:
A1:    What is the function of the check valve V1?
A2:    What function do the components V14 and V15 have in this circuit?
A3:    Which throttle is active here when lifting and retacting the cylinder 1A1?
A4:    Calculate the extension force of the lifting cylinder 1A1. Data: cylinder 50/8/500, system pressure 6 bar.