Posts Made By: Tapio Lahtinen

It would be nice to see full frame.
This looks more like field rotation to me.
I see that you have field rotator.
Is it functioning normal ?
Have you previously got good stars ?

Red cast is light pollution and is 'normal'.
You have couple of methods dealing with it -
1. light pollution filters (Astronomik CLS and Lumicon LPS are popular, astronomik has clip version which you could use with Canon).
2. after processing.

You have to do after processing anyway with PaintShop Pro, Photoshop or some graphics program that can handle at least curves and levels.
Attached is your image with minimal tweaking with PSP and curves/levels.

Dust is common problem with astro imaging. Again there are couple methods
1. cleaning sensors and/or filters
2. taking a flat frame (just google flat frame)

Registax is not very good software for deep sky imaging.
Try DeepSkyStacker which is very easy, powerful and free.
It can handle Canon raw files and you can use flat frames (and dark frames) with it.

Really nice looking.
What scope ?