If you use github pages, this is taken care of. Not only is there a very reliable backup, but you can have version control (ie, roll back to a previous version, or test branches of content).
What kind of "data" are you talking about here ? If it's binary data, it's not a good idea to keep it in a github repo. However, if it's csv, or yaml or some other form of text, then you can do that. However, as a general principle, it's a good idea to keep data in a data repository, which can be accessed via API. For this, the Sci-GaIA Open Access Repository that we wrote about in the deliverable. I would like to start a new topic however on this (data management in WIMEA RC3), since it could diverge from this one.
Finally, to answer your questions
One of the reasons we promote standards-compliant software and services is exactly this - they are easier to integrate into community portals. The idea of having a Science Gateway is not just a place to submit analysis jobs, but to have everything necessary to get the community's work done. It is perfectly acceptable to have things "scattered in various locations", since as a rule, you should use the "right tool for the job". Don't turn a wordpress site into a data repository, for example ! Using the right tool for the job makes it easy to do that job, and protects your investment in time for future users... the important thing is to integrate these tools into a gateway.
As far as I can see it so far, you need :
A document repository
- you need a place to publish documents, which will have a persistent identifier, so that people can reliably reference them and so that you can track citations.
- You need a library, so that you can expose a list of all of your publications to project reviewers, new members, etc.
A data repository
- These too need persistent identifiers
- It would be best if the identifiers were semantic (ie, you can create sets of data, which are linked to documents and scientific workflows. Data just by itself is often useless.
A public-facing website - this is to organise and expose the output of the project to the public, so that the work is visible. Integrations can be done on the backend using the APIs of the data and document repositories.
A community-facing science gateway - this is where the community actually collaborates. Teaching and learning materials, code... the "source" of your community. This is where github and the Science Gateway Framework comes in.
There is no absolute reason to have everything in the same place, they important thing is to integrate the services. If I have understood your needs, we can get started in implementing the needed services and integrating them. If there's something missing, let us know !