Mystere said:
More than likely, each successive build will be cumulative. Meaning, you only need to install the base ISO and then a single update to get the latest.

I am 100% sure the Technical Preview ISO download will not be updated, it will be the Build 9841 and only be replaced with the Consumer Preview first build ISO when it will be released. Each upgrade build will require the base 9841 build and contains all previous upgrades.