CO worflow: pick images and export the one that I modify

Hi
I have a very generic question about a basic workflow.

I come from Lightroom and I'm evaluating CO:

Usually I like to:
-look at all the images
-pick the one that I like (how to simply add a "pick" tag/flag with out any star rating or any colour rating in CO?
-filter the one that I "picked" and look again the the one that i picked, usually unpicking some of them (how to unpick in CO?
-"modify" some of the pictures I picked
-filter only the one that I "modified" inside the picked one.
-export to a separate folder only the one "modified"

is this workflow common in CO?
how can I do that?

I don't see any simply "pick" filter
how can filter the picture with adjustments only?

Thanks
p