Jammer questions

I would like to know how jammer works on the Mirage, and more importantly, how jammers work in DCS in general. That is why I've got some questions:

1. When I'm head on with an enemy fighter and he has me on my radar, should I turn it on, or better stay off?

2. When he fires a SAHR missile at me, should I turn it on, or better stay off?

3. If it's AHR missile(like AIM-120), is the answer going to be different than for 2?

4. If I am in a dogfight with an enemy fighter, should I turn it on, or better stay off?

5. How does it work if it's SAM?

Again, I am not asking about how it works in real life, but how it works in DCS. Thank you for your answers.

Jammers in DCS basicly work as noise jammers which shortens the range of which you can lock onto somebody and i (think) it also reduces the accuracy of radar guided missiles fired on you.

1. If he has you locked, turning it on might break the lock so nothing to lose there.

2. Just keep it on, i (think) it reduces the hit chance slightly as long as he hasnt achieved full burn through.

3. No.

4. No matter, you are well within burn through range and it shouldnt affect anything anymore.

5. Same principle as with planes.

Now what are the drawbacks of using the jammer? Well.. For one it is a huge "i am here" symbol that gives a rough location of where you are while having it off might keep you off somebodies scope.

If i am wrong feel free to correct me.