Would you know if I put purple forsting on white frosting and let it sit for 2 days. Will the purple bleed onto the white? Any input would be great. Thanks.

It depends on several issues:

Will the cake create condensation (will it be frozen then thawed)?
Will there be sunlight hitting the cake?
Will the icing the crusted (if using crusting BC) before putting the purple on it?

If the answer is yes to any of the above, you may have a bleeding issue.

As a funny story, I was transporting a 3D Duck on a blue cake (bathtub). The duck was in a box with a window and the sun wound up hitting it during transport. By the time I arrived on site, the heat from the sun had caused a little bit of the yellow icing to run onto the blue. there was a green stream of liquid coming from the duck into the "bathtub". It looked like he had peed himself!!!! We had a good laugh and then covered the accident with a trail of fondant bubbles.

I use a crusting buttercream and it will not be refridgerated or be put into the sunlight. It will sit in a box for 2 days. I want to use the purple for the writing and for my border work. So do yo think it will be ok?