if you have oral herpes does that mean you can not get genital herpes?

NO

You can either get the same strain genitally, or the other strain.

Having HSV1 orally seems to somewhat decrease the chances of getting it genitally, but having HSV2 orally does not seem to decrease the chances of getting HSV1 genitally. (I think I've got that right, someone will correct me if I have the strains mixed up!!) :)

But even if the chances are decreased, you can still get either strain genitally

From what I read in the handbook, I'm under the impression if you have any type of herpes anywhere and get re-infected with another type or place, the re-infection will be less severe since you have antibodies in your systom.

But Herpes acts in mysterious ways in different people.

Ain't that the truth!!