Each of these is a shipped surface, not a roadmap item. If a capability is listed here you can exercise it on the free tier unless the plan table says otherwise.
The uploaded PDF is scanned for signature lines, date fields and labelled text inputs, and those positions are written into the document before you open the editor. Anything it gets wrong you move by hand.
A document can carry several signers in a defined order. Each one receives a personal link, and the next signer is only notified once the previous signature is recorded.
A signing link can be held behind a code the sender shares out of band, so possession of the link alone is not enough to open the document.
Every open, sign and decline is recorded with a timestamp and source address. On completion the signed file is hashed and a certificate page is generated listing each signer and when they signed.
Any prepared document can be saved as a template with its fields and signer roles intact, then reissued to a new recipient without redoing the layout.
Send a document, read its field map, poll its status and download the signed file over /api/v1. Webhooks push completion events to your endpoint. Reference is at /docs.