More than one way is available to locate a Web page within a set of Web pages except where the Web Page is the result of, or a step in, a process.
Testing & RemediationHow to test: You need to open your site up and manually check that there is more than one way to navigate to all pages on the site. How to remediate: There are a number of ways to allow users multiple ways to navigate to all pages of your site. The two most prominent ways are to provide a search function and a site map. There are other ways such as providing a table of contents, providing a list of links to all other web pages, etc.
Questions and Answers
Nearly all elements can be given focus, and have their focus order changed using the 'tabindex' attribute. Elements on a page will be given focus in the order of their tab index. W3 Schools has a great explanation of tabindex here.
To navigate a website with the keyboard, you can start by hitting the tab key. You should see an indicator on the element that has focus. If it is a link, you can hit enter to go to it. While going forward through the tab keys is done with tab, going backwards can be done by hitting the shift key in addition to the tab key. When it comes to various input elements (radio buttons, select boxes), the arrow keys can be used on them once the element has focus.
This question depends on a number of factors including size of site, desired level of conformance, your developer's understanding of accessibility techniques, etc. Accessible Web is here to help. Reach out and we can discuss your site specifically.