1 - I wonder what is refered to by Keser Malchus, I assume this refers to his position as "Reish Mesivta" (apparently having 300 students,a huge amount for the time.) He was also very much involved in the ועד ארבעה ארצות hence the reference to תקנות לדורו and perhaps the Keser Malchus refers to this.
2 - The reference to commentaries on all Posekim - earlier and later - would imply that, at the very least, he also had commentaries on Rambam and Rosh. Presumably these were lost in the same fire with many of his other writings. Some of his Teshuos are in ShuT Geonei Basrai (IIRC), I would guess the rest are missing.
3 - No mention of his wife, Baila, the Sema cites her in the HaKdamah to Sema. Wikipedia quotes her son that:
בגמילות חסד, ביקור חולים ושאר מצוות. בהיותה בת חמישים עלתה לארץ ישראל, וכעבור שמונה שנים נפטרה שם בגיל 58, ונקברה סמוך לקברו של זכריה הנביא בהר הזיתים בירושלים (מתוך הקדמת בנו, ר' יוזפא, לחיבור דרישה ופרישה).