Cycling is a great sport for people that have problems with running.  The strength you gain, in many cases, will allow you to try running again.  As you build up strength around your knees and joints via cycling, many people who were unable to run have found running to be an option.  One down side to cycling is, its a very expensive sport to start.  You need a bike, helmet, cycling clothing, sunglasses, saddle bag, extra tube, tire lever, floor pump, a small mountable pump, water bottles etc..........That being said, cycling sounds to me like a great option for you.  You mentioned having a stress fracture, cycling is great for people prone to stress fractures, as there is no impact.  Have fun getting into cycling, please ask if you have any questions, we will have some answers!

As a bike shop employee, and a person who loves cycling I can tell you that MOST bikes out there, at bike shops, are good quality.  The bike world is too competitive for any one brand to make a product that is not on par with its competition.  The most important thing is FIT.  If you go into a bike shop and they dont spend a fair amount of time working on what size you need, then just find a different shop.  Finding the correct bike/price range is important for sure, but if the bike is not the correct frame size, you will not ride it.  Having a frame that is not the right size will create pain in different parts of your body.  Neck pain, lower back, hand numbness etc.  On a side note...I went to Kansas State and lived in Manhattan for 12 years!  Go Cats!  You will have to go to Olathe or Lawrence I would assume, to find a good shop.  Go to several shops and go with the one that spends the most time with you and listens to your personal needs.  Have fun and keep in touch.

You have made a very important observation.  You are correct, but not 100% on point with the way pricing goes.  Components DO scale with price, but so does the raw cost of the frame/fork...and with that cost comes performance.  Where you make your decision comes in geometry and engineering.  Not all road bikes are designed for the same riding position.  Look at top tube length, and headtube length to determine riding position.  In general the length of the headtube dictates how upright your riding position will be.  On many race/performance roadbikes the headtube will be, on a 54cm frame, 140mm.  On a 56cm, 160mm; 58cm 180mm...notice the patturn.  On a more upright road bike, the headtube may be 160mm on a 54cm frame, or 20mm greater per size.  Look at this on each bike you look at...the bigger the headtube, the more upright you will be.  Where brands make there money is how well they engineer a bike around different riding style.  In my opinion, the best race bike that is also comfortable is the Cervelo RS.  This bike is amazing, its based on Cervelo's all around race bike that won the Tour in 2008, but with a taller headtube.  The way the engiineers redesigned this bike to be more upright with out sacraficing on performance is astounding.  If this bike is more than you are looking to spend, let me know and I can offer you some more options, but if its anywhere near where you were looking to spend, go ride one and it will knock your socks off.  Have fun and keep the questions comming.

Cool, grats man!  That is a very good bike, and buying it used is super cool, as long as the fit is correct.  Two recommendation, take off the aero bars unless you are planning on doing Tri's.  You need to be comfortable on your bike as a road bike, dont monkey with the way it was designed by extending way over the front hub.  Second, take that bike to a shop that measures your body and get a proper fit...if they dont measure you, then go somewhere else.  Getting a proper fit is SUPER important...everyone is built with different lengths and proportions, make sure you are fit correctly, that will ensure you are getting the most amount of power out of your body and you will avoid injury.

I can get behind that thought of platform pedals as a stepping stone.  I know the pedals you refered to, the ones with platform on one side.  I would recomend just getting some ~$25 platforms and using them as you gain strength.  Then, move to something like the Look Keo Sprint pedals, or the Speedplay pedals.  Both have ther ups and downs but both get the job done very well.