How can one repent of all the aforementioned sins, and how can one avoid being punished for them on the Day of Resurrection?

The door of repentance is open and will not close until the sun rises from the west. Sincere repentance is accepted, no matter how great the sin. One who repents from sin is like one who has no sin.

As for sins between a person and their Lord (such as drinking alcohol), their conditions are: cessation [of the sin], regret, and a firm resolve not to return to it.

As for sins between a person and other people (such as theft), it is obligatory to return the rights to their owners, without informing them of what transpired.

Regarding giving abortion medication, nothing further than repentance is required of you, because the woman herself carried out the abortion.

As for slandering chaste women: if they know about it, it is obligatory to seek their forgiveness. If they do not know, then seeking Allah's forgiveness (istighfar) and supplicating for them is sufficient.