You don't have to close one eye to take a pic...and some pros even train themselves to stop closing one eye bc it really does strain the eye and cause tension there.
There are DSLR cameras now that do have "live view" - where you can "see" the picture on the screen, rather than through the viewfinder (like, my D90 has liveview). I'm not sure which Canons have it, but I'm sure some Canon folks would know
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