It's free! Here's the catch: there will soon be a small and competitive fee on NFT sales to fund development and new features.
Currently, it's just one person. If interest picks up, a DAO will be formed.
Yes, currently all content is pinned to IPFS via Filecoin, using Web3.Storage. Further decentralization is a high-priority upcoming feature. Currently, data availability cannot be guaranteed. Saved data is not private, but it may be encrypted in the future.
Nope! You can save and pin your changes to IPFS for free. When you're ready, you can publish the latest content hash of your website(s) to your blockchain domain(s). This will require a gas fee, but there is no markup or "convenience fee".