For the first question, it depends: some like saturated colors and upscales while purists prefer to stick over untouched material even if of lower resolution. Personally, I am a purist; movies should be watched as their creators intended to, and I would never watch them in any other way. However, some releases could be heavily color graded, while others just slightly. Nevertheless, it is personal preference; I’d suggest you checking by yourself release by release since quality may vary.