[Freesurfer] cortical parcellation: atlas modification and speed/accuracy trade-off

At times, I would like to use FreeSurfer to just produce cortical parcellation and do not need other results like subcortical parcellation and cortical thickness.

How can I run the bare minimum number of steps to generate the cortical parcellation labeled volume?

(Does anyone have a script that runs just these steps?)

Similarly if I want to speed cortical parcellation and can accept lower accuracy as a tradeoff, are there parameters I can set to enable such a speed/accuracy tradeoff?

Now on the flip-side, for other subjects I would like to change the granularity of the cortical parcels that FreeSurfer uses, to use finer parcels. How do I construct a new cortical parcellation atlas with more labels?

Best,

Albert