Duncan,
Here's a guide to setting gain and offset -
http://www.lightstorm.at/pdfs/QHY8_settings.pdf You will need a different offset for each gain setting you want to use. Start with a gain of 0% to get going.
I use the maxim sequence section to capture lights, bias, flats and darks. I use the focus section, set to continuous, to frame the shot. With binning set to 4x4, a 5 sec exposure and screen stretch set to high, I can see the target on screen to frame it.
I use Deep Sky to stack all these files, maxim often won't stack qhy8 images correctly for me. In DSS, under Raw/Fits DDP settings, go to FITS tab, tick monochrome and select QHY8 from the camera list. The first attached image is what I see in PS after stacking in DSS. The second is the same image after curves and levels. I sometimes use ddp in maxim to stretch before going to PS but for me it's not always successful with qhy8 images so normally I'll stetch the image in PS.
Don't give up, they are pretty good cameras for the cash.
I've added a single 10minute sub, shown in maxim and shot from a dark site, from that image set.