Sovrin code and Indy code both use a classic open source community governance process. Each repo has maintainers (see MAINTAINERS.md in each repo), and anybody can raise a PR. The maintainers for the various indy repos hang out in #indy-maintainers on Rocket.Chat, and discuss PRs and related topics. They also meet every other week to clear items out in more interactive fashion. There is also a working group meeting on Thursdays, and an agent working group meeting on Wednesdays. You can find these meetings in the Hyperledger Community Calendar (see https://wiki.hyperledger.org/community/calendar-public-meetings), if you’d like to attend.
The identity owner agreement was, I believe, a construct in Sovrin’s V1 Trust Framework, but I don’t believe it is modeled in quite the same way in the new V2 Governance Framework. In V2, I believe each transaction simply requires a signature over the hash of the terms and conditions that apply to the network. Those terms and conditions are quite simple and just ask you to attest to stuff like, “I agree not to submit transactions containing other people’s private data or intellectual property, child pornography, or other types of illegal content.”
As far as getting a DID written to the ledger, it depends on the pool (ledger) you are working with. If you are running your own pool as recommended in the Indy Getting Started Guide, you will have a trustee DID that can create steward DIDs, and then your steward DID can write other DIDs for you. This process is observable in many of the code samples (see indy-sdk/doc/how-tos). If you are on the Sovrin testnet, you can send a DID and public key to email@example.com. If you are on the Sovrin mainnet, right now I believe you need to get a steward to write it for you. All of these answers are likely to evolve, soon, into a dual model, where you can either write the DID yourself in self-service fashion, and pay a fee to do so, or you can get someone to do the write for you (sponsor you). When that evolution happens, I’m sure there will be documentation about the process.