Well if you bothered to read the GB thread, you'd notice that GPS doesn't work yet on GB. In fact, all location-based services fail in GB currently.
Should work fine on FroYo tho. As far as endlessly scanning, if you use QuickGPS in WinMo (or get a solid GPS lock in WinMo) before booting Android, it will reduce your lock times in Android dramatically. Currently our port of Android doesn't take advantage of any of the advanced features for GPS like warm injection. See
this thread for additional discussion on that topic.
As for your last question, "PS: if someone knows, does Sprint version of TP2 has radio hardware inside?" - uhhh... of course it does. It has cellular radio hardware, bluetooth radio hardware, wlan radio hardware, GPS radio hardware... there are many radios in every single cell phone on the market... Especially 'high-end' phones.