It sounds like you'd want to setup a template rig in 3D that does a turntable in the appropriate amount of frames for each item/character. Make the models, plug them in and render them in an orthographic angle.
That way you'd have consistent lighting, angles and number of frames for each thing at a press of the render button.
The downside is you have to make it in 3D, but logistically and consistency wise it would be a lot easier.
The one problem is pixel art is an artform in itself, it is difficult to replicate the precision of pixel art by having 3D models since it'll just try to anti-alias everything together. Not impossible, but would require some development time to get the shaders/post process right.
You should post an example of the style of artwork at the resolution you're looking for as reference for potential helpers.