There is many options available for the web hosting it depends on the financial constraints of the company. Most of the big companies would like to host their web hosting server in their premises since they want to have full control on it, small web msters like me :) will host the website in any of the statnard web hosting companies like Web Hosting UK and also you can register the Domain Names with the same company.
Once you host your website the basic set up for running your website is come to end. If you are a web developer then you will choose to design your website and upload it. it is not the case for all the webmaster many of them are not aware of the web design, so they will buy web designing pack from the same web hosting company. Most of the popular web hosting companies provide web designing tool kits for designing the eCommerce development websites .
Search Engine Marketing is very important for a website to increase the sales and revenue of the website. the more pages indexed in Google, more visitors com in to the website. This should be the final step once you have done with setting up the website and started adding contents into the website.