Get a temporary render target. You should dispose the returned handle when you're done to return the textures to the pool.
Divide the screen size by this factor. 2 would be half screen sized. 1 for full screen sized.
The format for the color buffer. If null we'll choose the most appropriate for where you are in the pipeline.
The format for the depth buffer
The number of msaa samples you'd like. Msaa render textures are a pain in the ass so you're probably gonna regret trying to use this
Number of mips you want in this texture. You probably don't want this unless you want to generate mips in a second pass