Is it now ok to create a new camera in the same comp and do something else?
Yes. You can add as many cameras as you like, but only the topmost one will be used for fianl rendering in areas where they overlap.
If I do create a new camera, do I have to give it similar settings to what my old camera ended with?
Obviously yes, if you want to retain the same look.
Is there any reason why this may be happening? Without the parenting, the texture is where I want it to be.
You are using a bad workflow. Simply setting something to 3D will always do so at the origin - middle of the comp, Z is zero. That, however may not correctly reflect any 2D layers in the comp and may explain your parenting issues - your camera simply is positioned relative to the Null and the null is not in the right place. so in so many words: You have it all backwards. Decide how you tackle such stuff before you even begin and set it up eitehr as full 3D with your camera rig properly in place already or 2D, but don't do these crazy things. It is bound to end in chaos. Even if you can fix it now, it will come back to haunt you later if you need to adjust something in the project. I also suggest you read a bit in the help. You seem mighty confused and your incorrect use of terminology is in turn confusing to people like me.
Yeah, been only working on this for 2 weeks and have to have a big project in very soon, so, I am still very new. Maybe there is a better solution to my problem then. Basically, I have a 2D background. I then have loads of text animations, and this is all 3D, and it zooms into the camera. Infact, what I have done is very similar to this
Now that part is done, I wanted to zoom in with the camera, so it looks like it is moving forward. For the tutorial above, the only layer which is 2D is the background I want to zoom into. So, if I use a null object, this needs to be 3D. Is there another way around this, maybe doing it another way?