I need Legal help for game releasing?

I’ve been working on a game for sometime now and I am getting closer to the finish product. Here’s my situation I am working alone with no help from anyone else except for websites. The models and animations I made in Blender 3D. The voice acting was made and edited by me using Ardour and Linux Multimedia Studio. However, I have use sound effects and music from AudioBooks, as well as textures from Textures.com.

My questions are:

Are these websites really royalty free? if not where can I get some that truly are royalty free? (and don’t break the bank)

Is there anything I need to worry about with the open source programs legal-wise?

If I get someone I know to voice act what do I need to know?

What do I have to do to protect my game from copyright infringement or any stealing?

If I want to promote my game via live stream what should I do first?

Any information it would be great!

Thanks

Are these websites really royalty free?
I suggest that you read the terms on the corresponding website. And if you don’t understand them, ask their support.