I am just starting out on my sumlimation jouirney. It has only been about a week now. I have not experienced any clogging issues. The only issue I am having so far is with the black as it comes out more brownish. Other than that Iit seems ok.
That depends on the size of the prints, the smaller the print the more you can print. If you leave it on, it goes through maintenance phase which uses ink, the second filling lasts longer due to how much is in fill tubes.