What should one who repents from sins and transgressions that necessitate many expiations, such as swearing oaths, making vows, and not fasting Ramadan, do? And is repentance or standing in night prayer sufficient to remove these expiations from him, or must they be fulfilled?

Congratulations on your repentance; we ask Allah to accept it. As for expiations: a binding vow must be fulfilled. If you are unable to fulfill it, its expiation is the expiation for an oath. As for a vow of obstinacy, its maker has the choice between fulfilling it or offering the expiation for an oath. Making up missed prayers and fasts is obligatory by scholarly consensus for anyone who missed them due to an excuse, and it is permissible for anyone who missed them intentionally. The expiation for breaking a fast in Ramadan is only obligatory if the breaking of the fast was due to sexual intercourse.