Yes, with the exception of the Personal License, whether your are indie, in a team or large studio you are free to use these assets in any commercial projects, including films, games, and architectural visualisation. The Personal License is strictly for non-commercial use. 

Yes, you can modify the 3D models, textures, and materials to suit your requirements. However, you cannot redistribute the modified or original assets directly.

Yes, the PBR textures can be used with other render engines or 3D software. However, you might need to adjust the settings according to the specific render engine or software you are using.