hdri is a special rendering method for lighting. check google for detailed info. i'm using vue to create myself a starting point. i'm actually not a good painter... therefor i need references. that's what i do with photo plates and 3d. it helps me to get started when i have a concept in mind. vue is a powerful program to arrange your scene. at the same time you can keep an eye on composition. it's not too powerful when it comes to modelling though.