How would I go about changing the number of planes a carrier can hold and how do i get it so that bombers can be carried too?

You would need to change the XML files Civ4UnitInfos.xml in there you will find:

<UnitInfo>
<Class>UNITCLASS_CARRIER</Class>
<Type>UNIT_CARRIER</Type>
<UniqueNames/>
<Special>NONE</Special>
<Capture>NONE</Capture>
<Combat>UNITCOMBAT_NAVAL</Combat>
<Domain>DOMAIN_SEA</Domain>
<DefaultUnitAI>UNITAI_CARRIER_SEA</DefaultUnitAI>
<Invisible>NONE</Invisible>
<SeeInvisible>NONE</SeeInvisible>
<Description>TXT_KEY_UNIT_CARRIER</Description>
<Civilopedia>TXT_KEY_UNIT_CARRIER_PEDIA</Civilopedia>
<Strategy>TXT_KEY_UNIT_CARRIER_STRATEGY</Strategy>
<Advisor>ADVISOR_MILITARY</Advisor>
<bAnimal>0</bAnimal>
<bFood>0</bFood>
<bNoBadGoodies>0</bNoBadGoodies>
<bOnlyDefensive>0</bOnlyDefensive>
<bNoCapture>0</bNoCapture>
<bQuickCombat>0</bQuickCombat>
<bRivalTerritory>0</bRivalTerritory>
<bMilitaryHappiness>0</bMilitaryHappiness>
<bMilitarySupport>1</bMilitarySupport>
<bMilitaryProduction>1</bMilitaryProduction>
<bPillage>1</bPillage>
<bSpy>0</bSpy>
<bSabotage>0</bSabotage>
<bDestroy>0</bDestroy>
<bStealPlans>0</bStealPlans>
<bInvestigate>0</bInvestigate>
<bCounterSpy>0</bCounterSpy>
<bFound>0</bFound>
<bGoldenAge>0</bGoldenAge>
<bInvisible>0</bInvisible>
<bFirstStrikeImmune>0</bFirstStrikeImmune>
<bNoDefensiveBonus>0</bNoDefensiveBonus>
<bIgnoreBuildingDefense>1</bIgnoreBuildingDefense>
<bCanMoveImpassable>0</bCanMoveImpassable>
<bCanMoveAllTerrain>0</bCanMoveAllTerrain>
<bFlatMovementCost>0</bFlatMovementCost>
<bIgnoreTerrainCost>0</bIgnoreTerrainCost>
<bNukeImmune>0</bNukeImmune>
<bPrereqBonuses>0</bPrereqBonuses>
<bPrereqReligion>0</bPrereqReligion>
<bMechanized>1</bMechanized>
<bRenderBelowWater>1</bRenderBelowWater>
<bSuicide>0</bSuicide>
<bHiddenNationality>0</bHiddenNationality>
<bAlwaysHostile>0</bAlwaysHostile>
<UnitClassUpgrades/>
<UnitClassTargets/>
<UnitCombatTargets/>
<UnitClassDefenders/>
<UnitCombatDefenders/>
<FlankingStrikes/>
<UnitAIs>
<UnitAI>
<UnitAIType>UNITAI_CARRIER_SEA</UnitAIType>
<bUnitAI>1</bUnitAI>
</UnitAI>
</UnitAIs>
<NotUnitAIs/>
<Builds/>
<ReligionSpreads/>
<CorporationSpreads/>
<GreatPeoples/>
<Buildings/>
<ForceBuildings/>
<HolyCity>NONE</HolyCity>
<ReligionType>NONE</ReligionType>
<StateReligion>NONE</StateReligion>
<PrereqReligion>NONE</PrereqReligion>
<PrereqCorporation>NONE</PrereqCorporation>
<PrereqBuilding>NONE</PrereqBuilding>
<PrereqTech>TECH_FLIGHT</PrereqTech>
<TechTypes/>
<BonusType>NONE</BonusType>
<PrereqBonuses>
<BonusType>BONUS_OIL</BonusType>
<BonusType>BONUS_URANIUM</BonusType>
<BonusType>NONE</BonusType>
<BonusType>NONE</BonusType>
</PrereqBonuses>
<ProductionTraits/>
<Flavors/>
<iAIWeight>0</iAIWeight>
<iCost>175</iCost>
<iHurryCostModifier>0</iHurryCostModifier>
<iAdvancedStartCost>100</iAdvancedStartCost>
<iAdvancedStartCostIncrease>0</iAdvancedStartCostIncrease>
<iMinAreaSize>20</iMinAreaSize>
<iMoves>5</iMoves>
<bNoRevealMap>0</bNoRevealMap>
<iAirRange>0</iAirRange>
<iAirUnitCap>0</iAirUnitCap>
<iDropRange>0</iDropRange>
<iNukeRange>-1</iNukeRange>
<iWorkRate>0</iWorkRate>
<iBaseDiscover>0</iBaseDiscover>
<iDiscoverMultiplier>0</iDiscoverMultiplier>
<iBaseHurry>0</iBaseHurry>
<iHurryMultiplier>0</iHurryMultiplier>
<iBaseTrade>0</iBaseTrade>
<iTradeMultiplier>0</iTradeMultiplier>
<iGreatWorkCulture>0</iGreatWorkCulture>
<iEspionagePoints>0</iEspionagePoints>
<TerrainImpassables/>
<FeatureImpassables/>
<TerrainPassableTechs/>
<FeaturePassableTechs/>
<iCombat>16</iCombat>
<iCombatLimit>100</iCombatLimit>
<iAirCombat>0</iAirCombat>
<iAirCombatLimit>0</iAirCombatLimit>
<iXPValueAttack>4</iXPValueAttack>
<iXPValueDefense>2</iXPValueDefense>
<iFirstStrikes>0</iFirstStrikes>
<iChanceFirstStrikes>0</iChanceFirstStrikes>
<iInterceptionProbability>0</iInterceptionProbability>
<iInterceptionLethality>0</iInterceptionLethality>
<iEvasionProbability>0</iEvasionProbability>
<iWithdrawalProb>0</iWithdrawalProb>
<iCollateralDamage>0</iCollateralDamage>
<iCollateralDamageLimit>0</iCollateralDamageLimit>
<iCollateralDamageMaxUnits>0</iCollateralDamageMaxUnits>
<iCityAttack>0</iCityAttack>
<iCityDefense>0</iCityDefense>
<iAnimalCombat>0</iAnimalCombat>
<iHillsAttack>0</iHillsAttack>
<iHillsDefense>0</iHillsDefense>
<TerrainNatives/>
<FeatureNatives/>
<TerrainAttacks/>
<TerrainDefenses/>
<FeatureAttacks/>
<FeatureDefenses/>
<UnitClassAttackMods/>
<UnitClassDefenseMods/>
<UnitCombatMods/>
<UnitCombatCollateralImmunes/>
<DomainMods/>
<BonusProductionModifiers/>
<iBombRate>0</iBombRate>
<iBombardRate>0</iBombardRate>
<SpecialCargo>SPECIALUNIT_FIGHTER</SpecialCargo>
<DomainCargo>DOMAIN_AIR</DomainCargo>
<iCargo>3</iCargo>
<iConscription>0</iConscription>
<iCultureGarrison>0</iCultureGarrison>
<iExtraCost>0</iExtraCost>
<iAsset>5</iAsset>
<iPower>16</iPower>
<UnitMeshGroups>
<iGroupSize>1</iGroupSize>
<fMaxSpeed>2.25</fMaxSpeed>
<fPadTime>1</fPadTime>
<iMeleeWaveSize>1</iMeleeWaveSize>
<iRangedWaveSize>1</iRangedWaveSize>
<UnitMeshGroup>
<iRequired>1</iRequired>
<EarlyArtDefineTag>ART_DEF_UNIT_CARRIER</EarlyArtDefineTag>
</UnitMeshGroup>
</UnitMeshGroups>
<FormationType>FORMATION_TYPE_MACHINE</FormationType>
<HotKey/>
<bAltDown>0</bAltDown>
<bShiftDown>0</bShiftDown>
<bCtrlDown>0</bCtrlDown>
<iHotKeyPriority>0</iHotKeyPriority>
<FreePromotions/>
<LeaderPromotion>NONE</LeaderPromotion>
<iLeaderExperience>0</iLeaderExperience>
</UnitInfo>

The bold <iCargo> entry is what you want to change to have the carrier carry whatever number you put in there

As for making it carry bombers

change this bold entry:

<UnitInfo>
<Class>UNITCLASS_BOMBER</Class>
<Type>UNIT_BOMBER</Type>
<UniqueNames/>
<Special>NONE</Special>
<Capture>NONE</Capture>
<Combat>UNITCOMBAT_BOMBER</Combat>
<Domain>DOMAIN_AIR</Domain>
<DefaultUnitAI>UNITAI_ATTACK_AIR</DefaultUnitAI>
<Invisible>NONE</Invisible>
<SeeInvisible>NONE</SeeInvisible>
<Description>TXT_KEY_UNIT_BOMBER</Description>
<Civilopedia>TXT_KEY_UNIT_BOMBER_PEDIA</Civilopedia>
<Strategy>TXT_KEY_UNIT_BOMBER_STRATEGY</Strategy>

to this:

<UnitInfo>
<Class>UNITCLASS_BOMBER</Class>
<Type>UNIT_BOMBER</Type>
<UniqueNames/>
<Special>SPECIALUNIT_FIGHTER</Special>
<Capture>NONE</Capture>
<Combat>UNITCOMBAT_BOMBER</Combat>
<Domain>DOMAIN_AIR</Domain>
<DefaultUnitAI>UNITAI_ATTACK_AIR</DefaultUnitAI>
<Invisible>NONE</Invisible>
<SeeInvisible>NONE</SeeInvisible>
<Description>TXT_KEY_UNIT_BOMBER</Description>
<Civilopedia>TXT_KEY_UNIT_BOMBER_PEDIA</Civilopedia>
<Strategy>TXT_KEY_UNIT_BOMBER_STRATEGY</Strategy>

Thank you very much.