Arrived at Miami Immigration after about a 10 minute commute from the plane where they had about 100 Kiosks which were mostly empty. Once checked in saw an agent and he took less than a minute to check our passports, take the kiosk receipts, and wave us thru. He did not stamp the TW's Thai passport, but I had experienced that before having it stamped at customs on the way out. (Note that usual US is Immigration check then customs check after baggage claim, same as Thailand).
We got our bags and headed to customs except there was no customs, just the exit door to the MIA terminal. An agent was leaning against the wall watching us all exit but no separate customs checkpoint. I went back to him staying my wife's passport was not stamped. He replied the US no longer stamps passports as they keep track of it electronically as we just needed to understand the visit was good for 6 months.
Personally I would rather they stamped the passport to eliminate any length of stay questions. What I did was staple her international bording pass into her US Visa passport noting the no stamp and specifying the 6 month expiration.
With a 10 year US Tourist Visa, holders will have their passport expire before the Visa expires. There is no switching the visa to the new passport, you just carry both your new passport and the expired passport with the Visa.