I don't know if you can handle this preemptively--you could try and call and see what happens. But note that some people never get the ads to begin with--you can just wait and see.
With TE3, you choose between 2 forms of the Guide format: the Grid Guide--the form that the cablecos tend to use; and the Live Guide, the format that TiVo came up with years ago and that some of us prefer. With TE4, the regular Live Guide format is gone and the Grid Guide format is the only one. Having said that, a separate, "mini" version of the Live Guide still can be accessed (that's the smaller Guide version that you get under TE3 when watching live television and you press the remote's Select button).
(I just tried what you said I get it now! )
Yep. With TE3, as you know, TiVo "marks" many primetime TV shows so that you can press a remote button at the start of a commercial break and skip the commercials. With TE4, you can set the box to skip the commercials automatically, no button press required.
(That I did not know cool!)
HDMI-CEC is a newer technology that lets electronic components talk back and forth to each other. A biggest use: you press a button on your TiVo remote, such as the TiVo button to get to your My Shows listing, and the TV turns on automatically while also going to the My Shows screen. Just a nice convenience, saving button presses.