What are the chances of having a lazy eye if i am nearsighted in one eye and farsighted in the other?

Yes, if you're a kid: Lazy eye is amblyopia, a developmental brain problem in which a child's brain gets a better image from one eye than from the other eye. The part of his brain that gets the good image develops normally; but the part that gets the bad image won't develop well, and the corresponding eye won't "see" well. An adult should not get a new lazy eye because the adult brain's vision area is fully developed.

Depends: It depends on your age and the level of disparity. If you are a teenager or older and it's not lazy now then it should not become. If you are younger then appropriate correction with glasses and patching (if lazy) should prevent.