I am wondering about the combat effectiveness of the saucer section of a Galaxy class starship is compared to the stardrive section.

I know that the saucer section can sustain a warp field but not generate one. I don't know if it can change direction. I also do not know how crucial warp drive is in combat, I think they combat generally happens at impulse.

So, what I would like to know is:

1. what the distribution of phasers and torpedo launchers is and if know what their angle of fire is(do either of the sections have blind spots they cannot fire in).
2. Do both sections have comparable shielding?
3. Is the stardrive section more or less manoeuvrable on its own?

Additionally, I see basically three reasonable situations where you would separate the ship: 1) To have multiple vectors of attack, 2) To leave non-essential personal behind and 3) You need to do a crash landing.

I have seen 2 and 3, but I am not sure I have seen a combat situation using both sections on a Galaxy class before. **Is multivectored attack viable in a Galaxy class or is that the just domain of the Prometheus class?**