Still waiting for my Nexus One to tell me that there is an update. =/

Oh. I am on stock ROM and haven't seen it.

I have some questions. I am finally going to root my Nexus One to customize and personalize my baby.
As mentioned, I am still on stock ROM (2.2). So I am wondering, would the rooting procedures be different since most of the guides for rooting were written prior to the introduction of Froyo . Also, by rooting, would it compromise my option of receive updates such as 2.2.1 via OTA, leaving me with no choice but to update manually ?

I have just gotten a new and higher capacity microSD card and I initially thought I can install the Android OS fresh and new onto the memory card but little did I know, everything is still intact even after replacing the memory card. Duh!!

I have just rooted my phone using Universal Androot and I thought of backing up using Nandroid. So I boot into console and click Recovery and it brought me to a screen where there is an exclamation mark with an android. Whats up ? What does this screen means ?

Does Titanium Backup perform the same thing as a Nandroid backup ? I have performed a full backup on everything using Titanium Backup. Is it still necessary to do a Nandroid Backup ?