First Major Moch Project

just did my first major job (wire removal) exclusively using Mocha Pro and the Remove Module. I learned a lot in the process, but have a few questions which will help next time.
Is it essential to track a static plane to replace part of a foreground? I often wanted just to mask in a splined area without the need to track but couldn’t do so.
I still find the first frame, last frame, frames before and after confusing.
Take the example of a 100 frame clip where I am using clean plates every 20 frames with “use clean plates exclusively”. Would the correct setting for frames before/after be twenty frames as the nearest clean plate will always be in this range so reducing rendering times?
Is the first frame and last frame referring to the frame range mocha looks at for it’s references, so in theory could be edited during the shot since it only needs to look at the previous and next frame containing a clean plate?

just did my first major job (wire removal) exclusively using Mocha Pro and the Remove Module. I learned a lot in the process, but have a few questions which will help next time.

Is it essential to track a static plane to replace part of a foreground? I often wanted just to mask in a splined area without the need to track but couldn’t do so.

I still find the first frame, last frame, frames before and after confusing.
Take the example of a 100 frame clip where I am using clean plates every 20 frames with “use clean plates exclusively”. Would the correct setting for frames before/after be twenty frames as the nearest clean plate will always be in this range so reducing rendering times?

Is the first frame and last frame referring to the frame range mocha looks at for it’s references, so in theory could be edited during the shot since it only needs to look at the previous and next frame containing a clean plate?