Regarding the firmware - I think we should just be thankful that it works and works well. Phatnoise abandoned the product, but at least it is a pretty reliable and stable piece of software.
For voices you need to search around on the forum a bit and then on the web. I have no idea what Alex sounds like. I have Jennifer - she came with the software that I have (PMM 3.92) and is OK to my ears, if rather too American.
There are plenty of third party voice tools out there using the standard Windows SAPI5 interface. The trick is to use voices which generate files with a 22kHz sample rate. Many only do 16kHz, which sounds fine from the PC, but you then have to convert for the Phatbox to play them and that often makes the quality suffer (in my experience, anyway).