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Polar alignment should be as tight as possible, or you will get field rotation as you track. A little bit might be just tolerable as stacking software can correct for rotation between subs. Any significant rotation within the period of a sub will cause star trailing. If you have poor polar alignment, the mount will need to regularly correct DEC, which can upset RA tracking on lower cost mounts, as Graham points out.
Don't know about that specific scope, but you need either a guidescope with a tracking camera alongside your main telescope or an off axis guider (OAG) which diverts light from your main scope to the guide camera. I use a modified 60mm finderscope with a QHY5 camera for the guidescope - if your scope takes 1.25 eyepieces, you should be able to do something similar. OAG gets rid of differential flexure, which can be a problem with some scopes and might be the best solution if you are imaging with a Newtonian scope.
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