The Docker image you're pointing to probably is built with the SYS CORE_SYMBOL. It's a way for Block.one to say: we're not running the mainnet.
You can use images we provide (at your own risk) here: https://hub.docker.com/r/eoscanada/eos/tags/
If you want
get_actions, you'll want to enable the
history_api_plugin (which serves the
/v1/history/get_actions endpoint and friends). Then, you can add:
filter-on = contractname # for a given contract
filter-on = * # to enable for all contracts
There is also a tool we wrote to boot networks, local dev environments, etc.. it's in https://github.com/eoscanada/eos-bios .. it accumulated a bit of cruft for the launch of the mainnet, but we're cleaning out anything extraneous to make it a nice developer tool.
Regarding disk space: as of block #4415524 (which just passed a few seconds ago), disk space is 1.3GB for the "blocks/" logs (which live on disk), and 11 GB for the "state/" (with
filter-on = * enabled and history api loaded), which lives in RAM (but also flushes to disk, through a mmap'd file).