Yes, that’s exactly what it is. If you have a transaction you have signed that may or may not ever be published, you can resolve this “unknown” state by spending the same input - which prevents play attacks.
Agree. Grin is different because of its interactivity - I’m also of the opinion that we should take advantage of that instead of making a hybrid transaction building out of it. A hybrid doesn’t bring the benefits of ITX nor does it achieve NITX so you miss on the good parts of both world.
It’s probably safe to say that most of us believe the naming could be much better. There was a long discussion on the naming of rounds here Transaction Round Naming Challenge but we have yet to reach a conclusion.
I’m glad people want to improve this part, it’s something I was hoping more people would be interested in for a long time. I believe we could move the transaction building process to a higher level, but this requires us to think about safe-cancel, one-time addresses and possibly other things as well - to prevent creating a flow that looks good today, but when you want to make it safe it hold grounds. This is also the reason why I asked Gene if he would be interested in improving the wallet experience. We need to figure out what we would consider good though and for this we need discussions like this.