Et si... il avait déjà quitté l'île ? Et que son bateau ait coulé quelque part au milieu de l'océan. {←PERIOD}
I find it tempting to rephrase the sentences above, using two “si”s:
Et si... il avait déjà quitté l'île ?
Et si son bateau a coulé quelque part au milieu de l'océan ? {←QUESTION MARK}
Question 1: Why does the “que” need to be used instead of “si” for the second time?
Question 2: Why does the subjunctive “ait” need to be used instead of the indicative “a”?
Question 3: Why does the second sentence in the original end with a period rather than a second question mark?