1. I would run the guiding assistant and set the settings as it suggests. See if that fixes the non-guiding issue.
2. What are you using for imaging? If your polar alignment is very good DEC drift will be small. Looking at your gear you could, for example, be imaging with ED80 + QHY8. This will give you a resolution of over 3 arc-sec/pixel (calculator is
here). If the drift is small you could image for quite a while before the trailing is visible.