In regards to SEO and having keywords within your domain name, it is beneficial to separate your keywords with a hyphen in a domain name. It won’t give you page one results alone, but it will help if you need to gain high rankings through search engine optimisation and promotion. Your domain name is a title for your website, as much as you would correctly title each post on a blog to summarise the content, you should do this with your domain name. Search Engines are categorising information for people to find, so a website selling Dog Houses would sensibly have a domain of Dog-Houses.com. Although you can still rank high for search terms no matter what your domain name is, it just makes sense to use your primary keywords if possible.