You really should read up on technologies before making statements like that.
The Pedo busts were not attacking exit nodes, it was an attack on the hidden services within the network, there is no mim attack on hidden services, as no one knows who is talking to who. What the FBI did was compromising the servers hosting the material, serving malware that send a single request out outside the TOR network.
Regarding 2; this only works if your software is perfect, which it won't be. The Pedo bust was abusing a known bug in Firefox 17, which had been fixed for quite a long time, it only takes a single bug in the stack to inject some data, that can be collected at some point later - Even if you only allow data through TOR and using SSL, there is nothing preventing FBI sending enough data about your local network, to help identifying you. (For instance, a quick wifi-scan gives you enough information to place my system somewhere in Denmark, using WIFI databases, like the stuff google collected with street view, you can probably pinpoint it even further)
While forcing SSL is a nice idea, generally, it wont work; as you said, people are doing mixed content - on top of that, it only takes a single compromised request to a CDN like jQuery, to have your system thoroughly compromised, see http://www.youtube.com/watch?v=ZCNZJ_7f0Hk (While they are compromising anonymous proxies, the attack will work just as well on TOR)