Integrating the Q2A theme with your WordPress theme is separate from SSO, but it uses a similar construct in that you have to be able to see the WP libraries from Q2A, hence the include statements at the top of the qa-theme.php. This means you can integrate the WP theme, and still use the Q2A user table. I can't see why you would want this in practice, but it is useful for testing, as you can focus on the theme, without worrying about problems from the user integration.
If this is on BlueHost, then they configure their servers in a strange way. There *might* be a way round this, but you would need some help from their tech support, and in my case, I got more help from the cat (similar help actually "Me? 'ow!").
The only thing I can suggest is to install your own WampServer, and configure it locally to remove the BlueHost issue. Or DreamHost do a weeks free trial (I'm not touting for DreamHost business, but so far, in about 4 months, they have been reliable, and faster for me - most of my traffic is US based, but in the UK, my NativeSpace sites also perform well with no integration problems).