I'm in essentially the identical situation with an Actiontec MI424WR REV I router and I need the same or similar information.
I assume that - like me - you need to keep the Actiontec router involved to handle FIOS TV and telephone, but want the ASUS to take over handling as much of the wired networking as possible and all of the wireless networking.
I don't know enough about routers to know whether the ASUS should be used as a "bridge" or as an "access point" (or whether those are the same thing), so that's something specific I'd like to learn.
Also, I know there are two ways the Actiontec can be connected to the ONT - Coax or ethernet. I've heard of people having just the coax connection to the Actiontec, so I assume in that situation the Actiontec internally does something to get the internet traffic to its RJ-45 ports.
But I don't know whether also having an ethernet connection from the ONT might affect how a new ASUS router should be connected. I found that my Actiontec does have both an ethernet and a coax cable connected to it from the ONT.
I read a suggestion elsewhere to connect a new router (e.g., the ASUS) to an RJ-45 ethernet port on the Actiontec and I had presumed that was necessary because the Actiontec would have to make the coax-supplied internet signal available to the home network via one of its ethernet ports.
However, when there is BOTH an ethernet AND a coax cable coming from the ONT to the Actiontec, I wonder whether it might be advisable (or whether it would make any difference) to connect the ONT's ethernet cable directly to the ASUS router first and then connect an ethernet cable from an ASUS RJ-45 port to an RJ-45 port on the Actiontec (assuming that FIOS TV, in particular still needs some access to the internet)?
So I, too, would be very interested in learning about settings for the two routers. But I also would like to learn more about bridging vs. access point usage of the ASUS, as well as whether it would be advisable to have the ASUS router "see" the internet signal first by connecting the ONT's ethernet cable directly to it rather than to the Actiontec.
I hope someone here can help both of us.