Here's my advice. If serious about getting a road bike then join Bike Radar and have a look and ask on their beginners thread here
http://www.bikeradar.com/forums/viewforum.php?f=40020 it's quite a bit more active but you tend to get more serious and helpul advice on this forum.
There are some muppets on there who are unhelpful and seem to just post on beginners boards to show off. Then again, if you are genuinely female or at least say you are you will get a lot more help. FYI that is not why I am helping you - just that you sound a bit clueless & we have all been there.
Changing riding position and getting used to it doesn't take long - about as long as SPDs.
To find the right size & make go to some bike shops and test them out - that's the only real world way of being sure.
Stems are often too long but this is a very easy & relatively cheap fix. What is more important is stand over height of the top tube and reach over the frame to the bars.
What's your budget? Once these things are sorted I recommend buying 2nd hand either on Gumtree or
Ebay or local press. You can pick up some real bargains but you need to know what you are looking for.
This gives you all the info you need about what parts and frame parts are what.
http://en.wikipedia.org/wiki/Racing_bicycle
Good luck