Oh my..I can relate with you for the whole time reading this. Every. single. point.
My boys are 3&half and 7 years old. And thr 7 years old is like yours picky and always battle with me how many more mouthful to go. Recently I went to the extreme, either you eat or you leave the table and I am fine with it. That shocked him a little as in the past I would give in to give what he loved to eat. Not anymore. And he learned not to be too choosy and give thanks for food. Aha!
We sure have lots of fun with the boys and yeap with the "fart" and "buttock" and "bum". Lol.
High-5 to you all the way from Malaysia.