Can't really help with the GPS unlock issue - AT&T didn't lock theirs.

There's a "Raphael CDMA" forum at XDA-Developers. That forum tends to be more technical in nature (and more snarky), so you might want to take a look at GPS threads there and see what they have to say.

The early TP ROMs did have GPS issues that updated ROMs have improved/fixed. It may be that the ROM is an issue and not the chipset/phone itself. Long lock times were common across the platform for many, many users without some significant tweaks. So it may be that your ROM doesn't have the GPS fixes that have been put in newer ROMs, and you might find those at XDA.