Yes, I know... all info is in the mission brief. But it does me no good to have that data five minutes before flight time.
Months ago, before "real-life issues" or changing work schedules disrupted things, I used to fly these missions with a four or five man Independent Bomber Group. Now, on Bomber Nights it's usually just me. Either way, I still enjoy the planning exercise for each upcoming mission.
Location of bomber base: "But Wespe, if we broadcast the location of the bomber base... then the opposing fighters will know where we're coming from!"
Well, duh! As soon as the mission starts, the opposition can see where all the bases are at. And some enterprising hero might also take the 15 extra seconds to click on the various bases to see which one the bombers are coming from to further refine his direction to the action, so it should be no really big deal.
Posting the location of the bomber base when announcing the mission allows people to plan primary and secondary routes to the target and disseminate that info to all concerned. What kind of info...? Azimuths to ground references and turn points and flight times to same, speeds and rates of climb to reach desired altitudes dependent upon distance to target, which angle to hit the target from to cause the most damage, etc.
The route is easy. Due south.
Yeah, if I want to fly directly into fighter opposition. I usually try to avoid the Corridor of Death.
This would have been a "Due South" mission but was planned to strike from the side... avoiding the waiting fighters

"Sevastopol Bomber Night" would have been another relatively "Due South" mission but we by-passed the target far to the east, turned around out at sea and struck from the south... due to the orientation of the target and to avoid running head on into enemy fighters.

This is why it's nice to know just where it is we're flying from.
As for requesting the bomb load-out data:
Various bomb loads affect several aspects of manual bombing data:
First, let me start off by stating that the airspeed gauge in the cockpit is relatively unreliable. If one is relying solely upon that, you could miss the target by as much as 200 meters. Much more accurate to go by "throttle setting" to define your indicated/true airspeed. Now, this might not be a big deal for those who just want to level bomb a city, but if you want to hit an oil refinery (and not the residential area next to it), accuracy is critical. Same for hitting a bridge, or sinking a skinny destroyer from 5,000m.
Here's a pic from working out the bombing data from another Bomber Night.
Different bomb loads affect air speed: The mission plan that was worked out called for dropping half the load over one target... flying to the next target and dropping the remaining bombs. The data provided allows to hit a 10m wide target from 5,000m (I use a Bf109 as a target)
Once the first load is away, the plane now weighs 500kg less and the airspeed increases. The second bomb drop required a different throttle setting to retain accuracy.
Different bomb loads affect sight angle:The bomb sight in this sim is not independently mounted, but is firmly attached to the plane. What does this mean for bomb sight data based upon bomb load? A plane carrying a 500kg bomb (all other data being accounted for) may have a bomb sight release angle of, let's say 40 degrees. But, the same plane carrying a 1,000kg bomb struggles a little more trying to fly level and not drop in altitude. It does this by assuming a slightly more "nose up" attitude. And as the nose tilts upward... the bomb sight tilts upward... and a different bomb sight angle (or other compensations) is called for.
Different bomb loads (externally mounted) impact airspeed due to drag: In order to work out accurate bombing data, one needs to know what the true airspeed is. Let's say that two planes are both carrying a 1,000kg load externally. One plane has a single 1,000kg bomb and the other has 2ea 500kg bombs slung underneath. The plane with the two bombs presents more of a frontal aspect to the oncoming air, causing more drag and reducing the aircraft's speed. Different bombing data needs to be worked out to compensate for this.
So yeah... It's nice to know ahead of time where we're taking off from and how we plan to get back.
As for the reason behind requesting what the available bomb payload will be... different loads require trial and error testing to work out data over a range of altitudes.
Just like for this upcoming mission. If I don't know what the load-outs will be... I can't figure out air speeds. There's quite a bit of difference in weight between a load of 4xFAB-1000 + 14xFAB-50 (4,700) and a load of 4xFAB-500 + 2xFAB-250 (2,500) and it all needs to be figured in.