The latest would be a link like /ipns/yourcompany.com, and you'd have a TXT record pointing at your node's IPNS hash (or an IPFS content hash directly) and you update it by either updating what your node's IPNS hash points to, or by editing the DNS record to point to the latest IPFS content hash.
No, if you put an IPNS hash in the TXT record you just update your IPFS node.
If you put an IPFS hash in the TXT record then you need to update that every time. I personally do this (domain name jes.xxx) because it means you don't need to leave your IPFS node running constantly in order for your IPNS name to be resolvable.
The record is:
jes.xxx. 300 IN TXT "dnslink=Qme12vJPtMpeUwmG2NLG11Q47jy2unSonegNJxQb9QgYax"
And I have a small shell script to update it automatically.
I believe that's what the previous poster means, you get a namespace that points to the canonical version of your resource, whatever that may be. Kind of like how HEAD is an alias for the latest SHA on a branch in git. But I don't know, this is just how I understood the previous comment.