First off, always mention if you're using DB Classic (DBC) or Dark Basic Pro (DBP). It really helps those trying to help you.
Scaling, either method works. One thing to keep in mind is your camera range. If you're clipping the camera at 3,000. You surely do not want objects that are hundreds of units across.
It sounds like you're building an arcade game. I suggest keeping the camera fixed and moving objects in and out of the camera's field of view (FOV). This also allows you to use 3D objects as part of your display for score, radar, etc.
If your game is more flight simulator like, move the camera instead.
As to scrolling backgrounds, one way is to have a long texture and a plain/plane for your background. Instead of moving the plain, just scroll the texture on the plain.
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TAZ