1) Tyvek is an air infiltration retardant membrane, no moisture reduction.
2) As mentioned by CSGuy , Tyvek is not an insulator.
3) Energy efficiency, do the following:
A) reduce air infiltration around your doors and windows (wheather stripping or storm windows),
B) use foam gaskets to seal all outlets, switches, etc on exterior walls,
C) insulate the roof,
D) insulated the floor,
E) LAST; insulate the walls, if possible also add an air barrier such as Tyvek to the outside of studs (NEVER inside).
4) What if anything is the vinyl installed over (ie is there wood siding or sheathing under it?)
5) Where is your home, are you on a coast line, are winters and/or summers extreme?
From what I can tell, your primary problem is that you are proposing a SOLUTION rather than QUANTIFYING the problem first. Products should only be identified after the problem areas(heat loss, etc) have been clearly defined.
Best of luck,
PS Call your heating fuel provider, they may have an energy audit program available to you at no cost.