Whilst you didn't mention in depth what your requirements are, I think that Atlassian provides all the products you would need to configure this. I would recommend Stash for source code management and integration, JIRA for issue tracking and interacting with your customers and Confluence for your Wiki/FAQ needs.
However, I think if you're considering starting out from scratch then you might find that you beenfit from working with an Atlassian Expert as they will be able to assist you with the entire process, from purchase to installation and configuration to get things setup exactly as you need them.
All the best,
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