I think the only way one can be saved without having true devine faith would be if one was Baptized on their deathbed and didn't know their Faith well yet wanted to become Catholic.
Since Caminus has addressed the second part of your post, I shall attempt to address this first part.
If I understand you correctly, in this case wherein the individual receives the Sacrament of Holy Baptism on their death-bed would indeed posses the supernatural virtue of faith, for by means of Holy Baptism the Holy Ghost infuses into the soul the three theological virtues, the infused moral virtues and His seven gifts.
This is why baptized children who die before the age of reason (whereat they begin to be morally responsible for their voluntary acts and thoughts) are regarded by Holy Church as being already in the possession of the Beatific Vision, as can be seen in the funerary rites for children as contained in the Roman Ritual. The Priest is vested in white and the votive Mass of the Angels may be said (never the Requiem Mass the rest of us would get, please God), and the head of the deceased child is wreathed with flowers and accompanied to the cemetery with the chanting of the Canticle of the Three Children
Benedicite.
In the hypothetical case you mention, if the person is an adult who has the use of reason, he must consent to be baptized and know the very basic rudiments of the faith (the Apostolic Symbol) if circuмstances forbid a full and proper catechetical instruction. I think that a quick instruction in the Mysteries of the Trinity and the Incarnation would suffice in extreme circuмstances (as when the person is about to die at any moment by reason of horrible wounds, or when an army is tearing down the doors and about to shoot everyone in the premises) in order for the person to be baptized quickly with natural water and know the faith he is embracing.
This is why every Catholic should be well instructed in their faith and in the proper procedure for administering emergency Baptism (which even layfolk can do): you never know whose soul you might just save.