Ok, to get you started...
allpayloads.dcg - you only need to add payloads other than default and none - one line for each. Data would come from DBW/STD/i18n/weapons_ru.properties
BF_109G6 A U3-MK108
[Name of plane from air.ini - air.xxx] [Type of loadout: A|B|D|T for Air/Bomb/Droptank/Torpedo] [Loadout name from weapons_ru.properties]
armor.dcg - data from DBW/STD/com/maddox/il2/objects/chief.ini and internet/books
1-PzIVF2 2 194208 194408 1-PzIVJ 06/06
[Name of chief from chief.ini] [Side 1|2] [Entered service] [Retired] [Upgrade type or none] [+friendly troops/-enemy troops]
class.dcg - data from air.ini, internet/books and IL2 folder but also compare to similar type in class.dcg already
BF_109G6 Bf 109G-6 de 2 1 1 194211 194412 BF_109G6Late Bf-109G-6 BF_109G2 5000 Meters 410.00 kph Default 410.00 kph
[Name of plane from air.ini - air.xxx] [Text friendly name] [country code] [side 1|2] [type] [flyable 1|0] [entered service] [retired] [upgrade type] [skin folder] [downgrade type] [transit altitude] [cruise speed] [range] [ingress speed]
[type]
1 = fighter
2 = level bomber
3 = transport
4 = ground attack/torpedo
5 = recon
6 = floatplane
7 = dive bomber
EDIT:
A few more...
gobjects.dcg - data from Chief.ini and Stationary.ini
artillery.Artillery$ZIS3 1 0 0 0 0 0 1 None
[object name] [First number is side 1|2, next five digits should be 0, then a 1 and then None]
gunits.dcg - data from Chief.ini and Stationary.ini
Vehicles.M3_Halftrack 1
[object name] [side 1|2]
payloads.dcg - data from weapons_ru.properties and air.ini
BF_109G6 R1-AB250 R6-MG151-20 R1-SC500 R3-DROPTANK R1-SC250 default
[Name of plane from air.ini - air.xxx] [Ground attack loadout] [Fighter loadout] [Bomber loadout] [Long range fighter loadout] [Anti-ship loadout] [?Recon loadout]