Clipless seems scary before you start riding them, but I am yet to know anyone that did not get used to (and dependent) on them fairly quickly.

As for pedaling, clipless helped me learn to apply more even force throughout the entire cycle of the pedal. This helps a lot going up hills. So I would say that you do pedal differently (in a positive way) with them than on flat pedals. You can get a similar result with clips and straps, but I found I had to get them cinched down tight (which was way more scary to get out of than clipless) to get the same benefit and that the top of my feet hurt/went numb.

I second cyccomute's suggestion to look at mountain bike style shoes. They are more versatile and walkable than road shoes. I like Lake and Specialized brand shoes, BTW.