I see the 6 perfection or rather the 5 spiritual faculties (faith, wisdom, concentration, energy and mindfulnes) as a whole that is developed together. they balance each other and slowly but surely each grows stronger by cultivating them in equal proportion.

As for the precepts.. They are originally meant as trainings. Which means you can slip up until you realize and experience that they are helpful on the path to liberation. I don't think they were ever meant to be taken at face value as commandments.

Sacrifice is something that is a result from these praises.
As for vows. Well to vow to undertake the training of keeping a precept is a vow, but leaves room to try again if you for whatever reason slip up.

I have to agree that a living master can be very valuable and speed up your progress.
But in this day and age is not absolutely necessary. People have been know to find what the buddha talked about with little guidance. That is not to say that teachers don't have tremendous value if you're serious about walking the path...

With Love
Eelco