I too tried a lot of bikes before choosing my latest. It was like doing the Goldilocks thing: Too tall, too shaky, too slow, ... and finally, just right. Geometry is important -- sitting at a comfortable angle, with your arms relaxed when on the handlebars, your legs at the most effective angles throughout the pedal stroke. A good bike shop will hold the bike steady and do at least a rough fit before sending you out for a test ride. Then on the test rides you'll want to compare how different bikes feel. I found the Jamis bikes to be the smoothest rides ever, but they had me sitting so high off the ground that I couldn't even get a toe down before dismounting, and at 57 I don't feel all that confident about tipping over and hoping my foot will be there as the ground approaches. I tried a Specialized, but found the frame so stiff that every pebble in the pavement gave me a jolt. That too made me a bit nervous when riding. I had a $200 Giant Sedona that was heavy and slow, but had some "senior" gears that I figured would get me up hills the rest of my life no matter how out of shape I get, but it was waaaay too slow if I wanted to go any distance now while I'm still in shape for some mileage. Finally I tried a Trek 7.6, which has a sort of "laid back" geometry that also provides some built-into-the-frame shock absorbtion. I also have an older Trek 7000 that I rode today -- a nice fit and a nice range of gears, a good smooth ride with just enough speed to keep me cool on a warm day, give a nice sense of freedom, and cut my commute time in half as compared to walking.

As for toe clips, clipless pedals, flat pedals ... if you can't stand having your feet in toe clips when on the stationary bike, then stick with flat pedals for now. Go with what's comfortable for you. I did make the switch to clipless last year. So far, so good ... that is to say, no falls due to forgetting to unclip. Today I rode my old bike with flat pedals and really missed being clipped on (strangely, clipless pedals actually clip onto your shoes, whereas toe clip pedals do not). 6 years ago when I bought this bike I did not even dare to _think_ about being clipped on, but now it feels much better that way. You'll know if and when you're ready to try it.

Other things you will need -- mostly just the helmet. Lights if you plan on riding after dark. If you'll be riding in traffic, I'd recommend a bright colored jacket or vest. If you're going to go on _long_ rides, I'd recommend a good pair of bike shorts. Also for longer rides or if you're nervous about falling, I'd recommend a pair of biking gloves. You might also want a small tool kit and pump for emergency repairs, again that'd be for longer rides. The bike shop will usually give you a water bottle and bottle cage for free. And you'll want some way to carry the few items you'll want along "just in case" (cell phone, a snack, some money, a jacket in case it turns cold or a place to tuck it away if it turns warm, that mini tool-kit and pump if you're riding some distance from home). For me that's my usual backpack, the one I carry to work anyway. You might prefer a small bag that fastens under the bike seat.