This presentation discusses top five things to consider before migrating an existing site to WordPress:
1) Transfer of SEO Ranks and Assets;
2) Native Approach Vs Copy-Paste Approach;
3) Complete Control of New Site from WordPress Dashboard;
4) Full Compatibility with WordPress Plugins and Widgets;
5) Complete Transfer of Content and Functionality (and Design if applicable).
In addition, the document comments on use of the automated conversion software for the WordPress Migration Jobs.