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.
Vander Name Meaning. You are fixed in your opinions, firm in your friendships and square in your dealings with others. You are an excellent worker. Since you are both possessive and emotional, you can be either very practical or very impractical and unpredictable.