Someone wants to buy me a portable jump starter "just in case" But i dont know if it will be powerful enough to start the vrs should the worse happen.

The starter is rated at 400A

i think what your saying there is that the portable jump starter is rated at 400A , therefore this will put out upto 400A , this will be more than enough to start the VRS i would imagine , the Fabia battery could be upto 720A