How flotilla shield works?

The way each ship's shield works is rather well-known.

However, flotilla shield lacks detailed description on its mechanism. Result screen also does not give detailed info about flotilla shield's effectiveness.

So, here's my questions.

Q1) Is shield capacity of the flotilla shield shared value in flotilla?

Q2) How can I calculate the absorption rate of the flotilla shield?

Q3) Will having both flotilla shield and standard shield decrease the damage twice while the capacity remaining?