1. When adding the Weapon for FSX to the IRIS A-10 Warthog, it does not change the VC 3D hud that is installed with it. It only adds the Weapon Control Panel, 2D HUD and 2D HUD Glass. I don't think you can get the guns to fire to where you point the gunsite. Only directly towards a specific direction (by changing the x, y, z coordinates and angle of incidence).

2. The M61 (6 barreled), only really has a rate of fire. You do not see the barrels rotating so whether it has 1, 6 or 7 barrels is not going to change anything. You can change the rate of fire, the range and the damages per shell to match the GAU-8 as well as adding a sound for it as well (if you can get your hands on it).

3. Changing the amount of ammo is done in the CSWeapon.xml. So open the CSWeapon.xml file with Notepad. Find the following section:

       <Weapon>
           <Gun>M61 Vulcan</Gun>
           <Shell>Vulcan Bullet</Shell>
           <Unlimited>1</Unlimited>
           <Station name="Nose" params="0,9,0,0,-0.039,0,1200" />
           <Mode name="AUTO" shotrate="100" setshots="0" sequence="1" skipFrm="0" />
           <Mode name="X10" shotrate="100" setshots="100" sequence="1" skipFrm="0" />
           <DefaultMode>AUTO</DefaultMode>
       </Weapon>

Change the 1200 to 1150 so it looks like this:

       <Weapon>
           <Gun>M61 Vulcan</Gun>
           <Shell>Vulcan Bullet</Shell>
           <Unlimited>1</Unlimited>
           <Station name="Nose" params="0,9,0,0,-0.039,0,1150" />
           <Mode name="AUTO" shotrate="100" setshots="0" sequence="1" skipFrm="0" />
           <Mode name="X10" shotrate="100" setshots="100" sequence="1" skipFrm="0" />
           <DefaultMode>AUTO</DefaultMode>
       </Weapon>

For the effective range, you need to change the <TargetRange>1500</TargetRange> to <TargetRange>4000</TargetRange>

       <Gun>
           <Type>MachineGun</Type>
           <Name>M61 Vulcan</Name>
           <Desc>M61 Vulcan six-barreled cannon</Desc>
           <HudString>GUN</HudString>
           <Pix />
           <ConeAngle>0.0015</ConeAngle>
           <TargetRange>1500</TargetRange>
           <Delay>0.0</Delay>
           <FxFire />
           <Sound name="..\..\..\Captain_Sim\Weapon\Sound\VulcanCannon.wav" loopBeg="0.5139" loopEnd="1.3059" finishLoop="0" gain="1.0" />

to this:

       <Gun>
           <Type>MachineGun</Type>
           <Name>M61 Vulcan</Name>
           <Desc>M61 Vulcan six-barreled cannon</Desc>
           <HudString>GUN</HudString>
           <Pix />
           <ConeAngle>0.0015</ConeAngle>
           <TargetRange>4000</TargetRange>
           <Delay>0.0</Delay>
           <FxFire />
           <Sound name="..\..\..\Captain_Sim\Weapon\Sound\VulcanCannon.wav" loopBeg="0.5139" loopEnd="1.3059" finishLoop="0" gain="1.0" />

4. Moving the guns position is in the same place as where you set the amount of ammo. It is not all that easy and it's fiddly. Not easy, but once you achieve the result, it is satisfying.

       <Weapon>
           <Gun>M61 Vulcan</Gun>
           <Shell>Vulcan Bullet</Shell>
           <Unlimited>1</Unlimited>
           <Station name="Nose" params="0,9,0,0,-0.039,0,1200" />
           <Mode name="AUTO" shotrate="100" setshots="0" sequence="1" skipFrm="0" />
           <Mode name="X10" shotrate="100" setshots="100" sequence="1" skipFrm="0" />
           <DefaultMode>AUTO</DefaultMode>
       </Weapon>

The parameters are: the first three are x,y,z in meters.  The next three are the angle of incidence (yaw, pitch, bank or bank, pitch, yaw). The final set of numbers is the ammo quantity.

5. I don't think it's possible. You have either the IRIS A-10 HUD or the CS 3D HUD. Setting up the CS 3D HUD is a whole new ball game and requires more tweaks and messing around to get it right. Take a look at the changes required for the another company F-16 by Lost in Isaan.

I only ever added Weapon for FSX to the IRIS A-10. I did not tweak the location of the guns, rockets and missiles. I had planned to do it, but never got around to it. Not only that. I have a bad habit of deleting all my hard work when I run into problems with FSX or the addon aircraft. When that happens, I have a hard time going back and completing it.

If you mess something up in the process, you will know when you open the Weapon Control Panel and turn it on. Your ammo will read all zero's (000 or 0000). So backup the CSWeapon.xml in the aircraft folder before you start making changes (if you decide to do it). ;)