Shield recharging components question...

[Taz-in-Space]

I have questions about those components that recharge a shield when hit by a weapon.
1)if you have a shield recharge component, say that gives 10 points back into the shields, do you get those points immediately or only at the end of a combat round?
2)will such a component work only when that particular component is hit or always work until destroyed.
3)what TYPE of shield energy is given: plain shields or phased shield?
4)does question number 3 depend on what kind of shields are present?
5)I've never used shield rechargers - am I missing out on a good thing?
6)Has anyone done a study on the usefulness of this kind of component?