The WPPSI-III has probably been dropped because the WPPSI-IV has been out for two years now, so legit evaluators should have moved on to the current instrument a year ago. (Unless, of course, you are in AU/NZ, in which case it was just released this spring.)

Yes, GAI is new to the WPPSI-IV. Pearson is slowly revising all the Wechslers to something that will look more like the WPPSI-IV (viz, the new WISC-V, which has a very similar index structure to the WPPSI-IV).
...pronounced like the long vowel and first letter of the alphabet...