Some Questions About Preparing Content For Marketplace Including Creating Blueprint From Mesh

Hi, I am new to UE4 and currently making a rock package for Marketplace.

1.What is the difference between “Convert selected components to Blueprint Class” and “Blueprint/Add Script” ?

  1. I have to prepare about 450 prefabs(16 rocks x 14 different materials for per rock). So it is time consuming to create BP one by one. I am looking for to create blueprint of mesh at once. I mean I want to select 16 rocks in the scene and want to make them BP with one click instead of doing this one by one.

  2. It is also time wasting to add all collider to all rocks one by one. I want to be able to add collider once and that should be done. Is there any way?