It sounds like you have only walking animation is present. To fix that, either animate, or create an empty animation called idle for idle animation. Re-export/save the animation file, and reload the model in-game (by opening and closing creative morph menu, B key by default), and that should be it.

Make sure to check Animation actions page for more information.

Unfortunately, no. Chameleon uses Blockbench's Bedrock model format exporter, and as far as I'm concerned, it doesn't support export of non-cubic elements. I'm not sure whether the format itself supports non-cubic models, but even if it does, there would be no way possible to support that feature until Blockbench will support exporting that data.

If you have a model that uses multiple textures, you'll need to put them together into a single texture. You can install Texture Stitcher plugin in File > Plugins > Available, and then right click somewhere in texture list, and pick Stitch all textures. That should combine all textures into one.