No, no, keep the granite and don't use limestone for the counters! Limestone STAINS and it reacts with acid (as does marble), so vinegar, lemons, tomatoes... they'll all leave marks. Granite is wonderful, you can cut on it, put hot pans on it, and it still looks good. (I have a granite table I've used for fifteen years of sheer abuse and it still looks brand new.)
As for hoods, the easiest hoods to install are the ones that match the range... everyone I know who's done a kitchen and used a different hood has regretted it. I have the Viking hood and stainless backsplash--with warming shelves--and it works beautifully. No, not as pretty as some others, but easy to clean grease off!