I rooted my TB a few days ago with the one-click (auto-root) method listed in the forum... it was sooo easy... I am now running dasBAMF 1.6.3 remix.
As for your radio... DO THIS RIGHT NOW, open "settings" - "about phone" - "software info" -
and then write down your current software number... Mine is 1.13.605.7 this is considered your radio. I say to do this becuase if you do ever play around with radio flashing, then you will know which one you had when you started... they are all basically the same to a degree, the only major different one is for gingerbread based ROMs. here is a link to all the TBOLT radios
[RADIO] The Obligatory Thunderbolt Radio Thread - xda-developers. I am currently using the second one on the list, I was using the first one but battery life was sucking down alot. just remember to keep track of which one you flash to your phone, and ALSO, as soon as you place it on the root of your SD and go into HBOOT mode (follow instructions for update), then immediately plug your phone in and remove that zip (PB05IMG) from the ROOT of your SD card... You can keep it on your sdcard if you want but just put it in a folder, thats what I do. then I use SuperManager (rootexplorer equivalent) to move them around instead of having to plug my phone onto my computer....
AND, I only had 1 reboot so far, but thats when I was experiementing with GB radios. so far, so good.
good luck and keep us posted