Since you don't know what size bike is best for you, buy your first road bike from a local bike shop that knows how to fit you. A bike that doesn't fit right is frustrating and a waste of time and money, regardless of how good a "deal" it may be. Once you have ridden for a few years and adjusted yourself to the riding position and adjusted your bike, you can upgrade if you want and you will by then probably know what size bike to get. Make sure you find someone at the local bike shop who knows how and is willing to take time to fit you. Have fun!!
PS - There is no "best womens saddle". You need to find one that fits you. See if your local bike shop will let you try a saddle and exchange it after riding a few times if it doesn't feel right. Performance does this, others as well.