Each use of AGPLv3 licensed software has to be reviewed to ensure that the obligations of the license can be and will be met (and also screen for cases where it is known that the vendor of software does not prefer a company like Amazon import the software under a FOSS license). Today we use AGPLv3 licensed software internally, and include AGPLv3 licensed software in Amazon Linux (Ghostscript, in particular).
> Does Amazon contribute funding back to the software projects they offer as a service?
Yes, in varying ways. For example, it is not easy to provide "funding" for something like Apache Kafka. You need to have people working on the upstream.
> Does Amazon contribute code changes back to the software projects they modified when offering them as a service?
Yes, but not all changes are appropriate for upstream.