And as I wrote -Shvus D’shvus would be Mutter since it’s L’zorech Mitzva (Shabbos).
Not if it was an extra tavshil.
No, he might have a Chulent for one day meal and not for the second (Shalosh Seudas).
You have a good imagination, inventing a minhag and tzorech to have cholent for seudah shlishis.
“Whatever you call not having a cholent, the R’ma is not being mattir amira l’akum for it (on a d’oraiso).”
Prove it.
253.