Of course, "it depends", but I would recommend two apps based on your description. Managing blog like website content is distinctly different from managing a shop. With two apps you can make changes to one without having to worry about the other. Often you will want a "content management" like system such as Radient or Locamotive for those types of things.
Of course, you don't have to do that and can keep it all in ror-e, but then expect to do a fair amount of modification to suit your scenario. Just my 2cents, Dave might have more wisdom.