QWhen I have 0 cards in my deck, can I use hBP02-084〈Mikkorone 24〉from hand?

ANo, you cannot.
You cannot just roll a die if you cannot draw cards from deck.

QWhen I have only 2 cards in my deck, can I use hBP02-084〈Mikkorone 24〉from hand?

AYes, you can.
In this case, roll the die after drawing 2 cards. Regardless of the outcome, resolve it as if nothing happens.

QDuring my main phase, I used hBP02-084〈Mikkorone 24〉and hSD01-020〈Circle of hololive Listeners〉, and rolled 1 die for each of them.
After, I used the Arts "Legend of My Supremacy" of hBP04-059〈La+ Darknesss〉, how many times "a die was rolled" would be counted by the ability?

AThey were rolled by an ability, even if they are from support cards, so it would be counted "2 times".

QWhen hBP02-084〈Mikkorone 24〉 is used, and 2 or 4 were rolled for the die roll, must I draw 1 card?

AYes, if 2 or 4 were rolled, you must draw 1 additional card.

QWhat happens if 1 is rolled when hBP02-084〈Mikkorone 24〉 is used?

AOnly the text for "Draw 2 cards" will be resolved.