[2312222]

for Nr1:

I would create the building, define the (firing) primary weapon, say we call it BuildingWeapon01 and then copy the weapon's entry in the weapon.ini and create another weapon called BuildingWeapon02.

I would then remove the damage parameters, all the fx and so on so that the weapon actually "exists" but is not able to cause any pain to your enemies. Than I would copy and change the ranger's code for the building and define a primary AND a secondary weapon in the FactionBuilding.ini. So that the program is able to really switch the weapons.

I may show it with the code from the US Strategy Center:

FactionBuilding.ini:

Object AmericaStrategyCenter
    DefaultConditionState
      Model           = ABStrategy_A8
      WeaponLaunchBone  = PRIMARY Muzzle
      WeaponMuzzleFlash               = PRIMARY MuzzleFX
      WeaponRecoilBone                = PRIMARY Barrel
      WeaponLaunchBone  = SECONDARY Muzzle
      WeaponMuzzleFlash               = SECONDARY MuzzleFX
      WeaponRecoilBone                = SECONDARY Barrel
      Turret                          = Turret01
      TurretPitch                     = TurretEL
      HideSubObject   = Chassis
    End

  WeaponSet
    Conditions           = None 
    Weapon               = PRIMARY StrategyCenterGun
    AutoChooseSources    = PRIMARY NONE
    Weapon               = SECONDARY StrategyCenterGun2
    AutoChooseSources    = SECONDARY NONE
  End

Weapon.ini:

;------------------------------------------------------------------------------
Weapon StrategyCenterGun
  PrimaryDamage         = 200.0            
  PrimaryDamageRadius   = 25.0      
  ScatterRadius         = 15.0
  ScatterRadiusVsInfantry = 15.0     ;When this weapon is used against infantry, it can randomly miss by as much as this distance.
  AttackRange = 400.0
  MinimumAttackRange = 100.0
  MinTargetPitch = 45                         ; we may not target anything outside of this pitch range
  MaxTargetPitch = 80                          ; ditto
  DamageType = EXPLOSION
  DeathType = EXPLODED
  WeaponSpeed = 150                           ; dist/sec 
  WeaponRecoil = 5                            ; angle to deflect the model when firing
  ProjectileObject = StrategyCenterArtilleryShell
  FireFX = WeaponFX_GenericTankGunNoTracer
  ProjectileDetonationFX = FX_ArtilleryBarrage
  FireSound = StrategyCenter_ArtilleryRound
  RadiusDamageAffects = ALLIES ENEMIES NEUTRALS
  DelayBetweenShots = 7000              ; time between shots, msec
  ShotsPerBarrel = 1                   ; By default, shoot one shot per barrel
  ClipSize = 0                    ; how many shots in a Clip (0 == infinite)
  WeaponBonus = PLAYER_UPGRADE DAMAGE 125% ; UraniumShells

  ; note, these only apply to units that aren't the explicit target 
  ; (ie, units that just happen to "get in the way"... projectiles
  ; always collide with the Designated Target, regardless of these flags
  ProjectileCollidesWith = STRUCTURES WALLS 
End

;------------------------------------------------------------------------------
Weapon StrategyCenterGun2
  PrimaryDamage         = 0.0            
  PrimaryDamageRadius   = 0.0      
  ScatterRadius         = 0.0
  ScatterRadiusVsInfantry = 0.0     ;When this weapon is used against infantry, it can randomly miss by as much as this distance.
  AttackRange = 0.0
  MinimumAttackRange = 0.0
  MinTargetPitch = 45                         ; we may not target anything outside of this pitch range
  MaxTargetPitch = 80                          ; ditto
  DamageType = EXPLOSION
  DeathType = EXPLODED
  WeaponSpeed = 150                           ; dist/sec 
  WeaponRecoil = 5                            ; angle to deflect the model when firing
  ;ProjectileObject = StrategyCenterArtilleryShell
  ;FireFX = WeaponFX_GenericTankGunNoTracer
  ;ProjectileDetonationFX = FX_ArtilleryBarrage
  ;FireSound = StrategyCenter_ArtilleryRound
  RadiusDamageAffects = ALLIES ENEMIES NEUTRALS
  DelayBetweenShots = 7000              ; time between shots, msec
  ShotsPerBarrel = 1                   ; By default, shoot one shot per barrel
  ClipSize = 0                    ; how many shots in a Clip (0 == infinite)
  ;WeaponBonus = PLAYER_UPGRADE DAMAGE 125% ; UraniumShells

  ; note, these only apply to units that aren't the explicit target 
  ; (ie, units that just happen to "get in the way"... projectiles
  ; always collide with the Designated Target, regardless of these flags
  ProjectileCollidesWith = STRUCTURES WALLS 
End

Then you need to add the buttons to your commandset.ini and commandbutton.ini.

You may try to disable the damage parameters also with an ";" but I don't now whether that is possible. If it crashes look at the "ReleaseCrashInfo.txt". Simply search for it using the search tool of windows. It often tells you where to look for INI errors.

for Nr2:

again take a look at the Strategy Center's code:

  ArmorSet
    Conditions      = None
    Armor           = StructureArmor
    DamageFX        = StructureDamageFXNoShake
  End

you see the line Conditions = None? Copy the code and insert FIRING_A so that when the building fires with its primary weapon it has another Armorset:

ArmorSet
    Conditions      = FIRING_A
    Armor           = StructureArmor_FIRING
    DamageFX        = StructureDamageFXNoShake
  End

ArmorSet
    Conditions      = None
    Armor           = StructureArmor
    DamageFX        = StructureDamageFXNoShake
  End

You need to define a new Armor in the armor.ini called StructureArmor_FIRING or so and change the parameters.

I hope my tips help you but I must say I did not test them so good luck!