Regarding the third way of acquiring a wife through kiddushin, through relations, would that require the female to have a get in order to marry someone else? Do baalas teshuvas require get from previous boyfriend before becoming observant? Would she be allowed to marry someone free and clear if she met the right one tomorrow?
There is no need for the baalas teshuva to receive a get, if the relationship was merely one of a friend, not a marriage. Not that such a relationship is permitted, but whatever was done, was not with the intent of being husband and wife, rather friends without the marriage factor. If they would have applied for a civil marriage, that is more serious, however when it is only on the level of friends, there is no kiddushin involved.
Igros Moshe E:H 4-40, Tzitz Eliezer 2-19(5).