I was told I can silk screen my registration marks on to to my Vinyl is this true.

Next is there a method to where I can line up my vector image with my silk screen. So that very time I silk screen and run the vinyl with the registration mark thru my plotter it will cut out exactly right every time.

There is no need to print registration marks.

Preferably use a vacuum platen (not absolutely required, but it makes the job a lot easier). Make stops, on the platen, for one side and the end of your decal blanks using masking tape.  This positions every print exactly the same on every blank.  You will also have to create side stops on your cutter.  The hard part is loading each blank precisely in the same starting position on your cutter.  You will have to make adjustments to the position of the design in the cutter software to get it to cut where you want.  You are now ready to screen your blanks and then cut them on you plotter/cutter. 
It is very labor intensive, but can be done.