So say ics comes out today. Can I still fxz back today and still get the update today?
Most likely you won't get the update over the air (OTA) today if ICS "comes out" today. First step is for them to do a "soak test" - which just sends the OTA update to a limited set of folks that have pre-registered and been pre-approved to get it. The reality is - if someone who's a member of that soak test group gets the update today, they'll likely post it to a public place where you can install it manually. So, can you "get the update over the air (OTA)" ?? probably not, but can you install it? most likely you can (assuming someone posts the released update file).
Welllllll, it's been known that some people who are not on the soak test get the OTA, so it is possible if you were on .905 to "Check for updates" and have ICS appear. There's no guarantee that it'll happen, though.
No, not really. When you go back to .905 you can check for updates and ICS should be there when it's available to be pulled (generally the day after it's pushed).
You can also go forward now to .247 which should be the same as the OTA. Take a look at SamuriHL's House Of Bionic - DroidRzr.com for more info.