Modified Calorie/lowering calorie number/splits/abs

Hi! I read an article about how to get abs. It seemed pretty reputable, the person who wrote it has 18 years of weight training and has abs.
Without going into detail of what I read-it's lengthy, I thought I would modify my calorie intake on my fitness pal. Has anyone does this?
Did you face any problems or bumps in the road? Anything I can lookout for? Any advise? Anything encouraging ?
I would like abs, I would like to step it up (just a half step or maybe 1 step) to the next level, I have only 20 pounds until I reach my goal, but I want to add on something to avoid getting bored.
My question is, has anyone cut their calorie deficit? What did this do? Did it help anyone? Why did other people do it?
Has any of the females on here had babies and then got abs at some point afterwards? If so, what did you do, for how long/how long did it take for you to do, and anything else you want to add.
To the people who have abs-what are the best exercises? How long and often do you do them?
Has anyone on here learned to do a split since starting on my fitness pal? How long did it take? How often did you stretch and for how long at a time?
Thanks for answering my questions and reading my post