yanskasso,
You said that your worst pain is a sharp, shooting pain between your shoulder blades. Usually that's caused by too long a reach to your handlebars. Over a long distance, it can cause severe pain! Even a short distance, if it's windy and you're gripping the bars tightly can cause pain and tightness. A shorter stem might help. Is it possible that your frame is too big for you? Whatever bike you get, be absolutely sure that it is a good fit for you. A less upright position is not necessarily going to be a bad thing for you. What you want to avoid is being too stretched out and putting too much pressure on your hands and arms. You need to be able to keep a bit of a bend in your elbows and be able to comfortably reach the bars. That helps absorb road shock. Another option you could try would be aerobars........... they do give you different positions for your hands and might help relieve some nerve compression for you.
As for the shoes vs. hiking boots, I don't know what to tell you. Are the hiking boots you wear wider than the cycling shoes? Maybe your feet need more room and you could find a wider cycling shoe? Normally, people have trouble with numb feet if they're NOT wearing cycling shoes. Maybe someone else will have some ideas for you on this one. Lots of experience on these boards......
Good luck on the bike search. I certainly understand the "I want one NOW!" feeling.
annie
Time is a companion that goes with us on a journey. It reminds us to cherish each moment, because it will never come again. What we leave behind is not as important as how we have lived." Captain Jean Luc Picard