I find it hard to see both Journal and Q&A on the same page. Not from a technical stand point - We can just plug both there, no problems. But from the end user point of view you would be mixing 2 different major call to actions on the same page - Ask questions on the Q&A module and post updates to the journal.
I think the end result is a bloated page.
But to answer your question, these 2 modules don't work together. Not they they will conflict. No they won't. But there is no interaction between them. So to your point, you can just plug them both on the same page without a problem.