The second one is charging hourly. We tend to prefer hourly fees on projects that are particularly open ended or very small scope. Our hourly rates are currently between $60 and $120 per hour depending on who is doing the work.
The word sonder exists, though. It means to probe, and in a more specific use, to test the depth of something. The word sound (as in the water feature) is a cognate, both related to the Old English sund meaning to swim, or the sea. I can't really think of an English equivalent that's specific beyond mere awareness.
Yoder is a surname that originated from the Canton of Bern in Switzerland. The name dates back to at least 1260, and is a shortened version of the name Theodorus. The surname Yoder is an Anglicized spelling of the Swiss last name Joder. Joder, in turn, is a shortened version of the name Theodorus. Saint Yoder is a patron saint of Valais, probably the first bishop of Octodurum