I enjoy your site very much! Thank you for all the great information!
Regarding this statement -
"In EIGRP we can use the network 0.0.0.0 command to advertise this. This might sound strange but it works, normally you can only use the network command to advertise networks on interfaces but EIGRP wil [sic] make an exception for this default route."Rather than an exception, isn't this the equivalent of "network 0.0.0.0 255.255.255.255"? EIGRP will use a classful wildcard if none is provided, so 0.0.0.0 will count as a class A.
Testing on IOS 15.2(4), “network 0.0.0.0” enables EIGRP for all interfaces. If you have any static routes to Null0 (default or not), these count as a directly connected interface (this can be confirmed by “sh ip route”) and thus are also advertised. Likewise, “redistribute connected” should also work for Null0 static routes, though they will count as EIGRP external routes.