Luckily, the keys are in order on the keyboard - w,e,r,t, ect. Press F1 to open keybinding window and scroll to Hotbuilding section. It does this by having multiple structures/units bound to the same key, which you press multiple times to cycle through. Hotbuild is a mod which lets you quickly order buildings and units via hotkeys instead of having to click the build menu.
Multiple T2/T3 factories and T2/T3 engies to build and assist are now cost efficient (Thanks to Rienzilla and Zock) Multiple factories or more than one higher tech engy were very inefficient. Only T1 engies were viable to produce higher tech units or assisting buildings. They don't require any installation and will probably break if you try to install them, simply enable the corresponding options in-game. These mods are currently integrated into FAF.
