Fruity Wrapper - Wrapper control options (1, 3 & 4) are common to all plugins (Native, VST & DX), while the Plugin options (2) only appear on Wrappers that are hosting VST & DX format plugins. The Wrapper provides compatibility with the VST and DX plugin standards (the screenshot below demonstrates the Fruity Wrapper hosting a fictitious 'Poi Poi' VSTi plugin). For more information on installing and using 3rd party VST/DX plugins, click here.
The Plugin Options (1) to (4) are explained in the Fruity Wrapper section of the manual.
FL Studio supports plugins with multiple inputs/outputs, set in the Fruity Wrapper Options (2).
For more information on installing 3rd party plugins, see the section on Installing Plugins.
FL Studio supports VST, VSTi, DX & DXi plugins along with Image-Line's own 'Fruity Plugin' format.
The Fruity Wrapper supports DirectX plugin instruments & effects. DirectX plugins are registered on installation directly in Windows, so FL Studio will detect them no matter in what folder they were installed. However, for the DirectX plugin system to work, you must have the latest DirectXMedia installed (it's now included in DirectX run-time installation, that can be downloaded from www.microsoft.com).
VST2 instruments & effects are supported in FL Studio by the Fruity Wrapper (instrument & effect versions).