Improve existing basic wordpress site website

I currently have a very basic online store website developed through wordpress that has been put together by a friend who only has minimal time to work on it. It is very basic with the bare minimum of information; I want a great looking home page and appropriate associated pages. The logo on the home page is not what I want; I have put together a basic picture for my company logo that I would like made to look great! I think the shopping cart also needs a little work; can a computerised sales receipt be generated automatically with each sale to be printed and sent to the customer? So basically I need a simple wordpress theme with a main column and a side bar, a simple custom designed banner/graphics, based on the theme/design I have in mind (I have a basic picture/design printed out that I can send as required to go from there). The theme needs to incorporate neatly with Wordpress simple PayPal cart, and have easy formatting when adding new products in a list (i.e. same spacing when there is a button on the line or not). I also want to have my site appear high up the list on Google and other search engines. Most of the work is already done, I just need a professional to go through and tweak it up to a great looking website!