For what is worth and my limited experience, I have the asi462 and I am getting frame rates of 304 on Mars ang Jupiter at a ROI of 640x480 and the exposure is still good enough to see the planet, histogram of 60-80%. Saturn I get close to 200. I did Neptune recently and it dropped to 19.I have an 8" Dob and I am manual tracking in that ROI, it is hard work but I enjoy it.
Regarding size, i use a 2x barlow or 2.5x powermate and the images are good size, unless you are seeking images that feel your monitor then you will resize but lose resolution.
Finally, ask questions and experiment. I have only been imaging for a year or so. Once you have the capture in your hard drive you can try until you get something satisfactory. Play with the capture settings. Post it here and seek feedback. Then try again. Depends on the capture quality every time, you may have to change the processing.
Looking forward to seeing your images.