Why not use Confluence for the website? Iam using it for some projects and it is really useful (configurable, keep history, give rights to some users to edit some pages). Indeed it's a wiki
Here an example with an existing project:
I have seen that a free license is available for opensource projects by filling this form:
There is a last issue which is where to host the confluence instance but it seems it's maybe possible to have free hosting. Looks at this post:
Also, I offer to transfer the existing web pages to the confluence if you decide to switch to it.