Code:
Swordsman 50 Brew 1 Platinum Sword
Mounted Swordsman 50 Brew 1 Platinum Sword 1 Battle Horse
Knight 50 Brew 1 Battle Horse
Mounted Marksman 50 Brew 1 Arquebus 1 Battle Horse
Marksman 50 Brew 1 Arquebus
Armoured Marksman 50 Brew 1 Arquebus 1 Platinum Sword
Besieger 50 Brew 1 Mortar
Platinum Swords :::
Platinum Weaponsmith 38 mins 4 Platinum 32 Coal = 1 Swords
Platinum Smelter 18 mins 2 Ore 16 Coal = 1 Platinum
Battle Horse :::
Elite Stable 12 mins 1 Saddle Cloth 1 Horse = 1 Battle Horse
SaddleCloth Weaver 12 mins 2 Woolen Cloth 1 Platinum = 1 Saddle Cloth
Weaver 6 mins 3 Wool = 1 Woolen Cloth
Homestead 6 mins = 1 Wool
Arquebus :::
Arquebus Maker 38 mins 8 Mahogany 2 Gunpowder = 1 Arquebus
PowderHut 18 mins 6 Saltpeter = 1 Gunpowder
Mortar :::
Foundry 38 mins 6 Gunpowder 1 Wagon = 1 Mortar
Wagon Maker 25 mins 6 Mahogany Planks 2 Wheels = 1 Wagon
Wheel Maker 18 mins 3 EWL 6 Iron Bars = 1 Wheel
Mahogany Wood Sawmill 15 mins 1 Mahogany = 1 MWP
From that you should be able to deduce that you will be focusing on, in order of cheapiness:
Knights - though cheapest, you will likely use/lose more Swordsmen in battles
Swordsmen
Mounted Swordsmen
With possibly Marksmen as a similar cost to Mounted Swordsmen depending on your economy balance and whether you want to produce Arquebuses 24/7 or just as needed.
The other troops will likely be a standing army, basically train 200/250/270 and then let the weapon production pause until needed again.
In my opinion therefore:
One powderhut should be plenty (after you make 270 Mortar it is mainly only turned on to make Arquebus, do Scenarios, upgrade things maybe)
One stable should be plenty - only need one horse per 12 mins to supply Elite Stable
Titanium? ... I cannot see where this might be needed, except lvl 6 upgrade of FairyCastle
Coal... enough to support your choice of platinum chain