AGI
Yes you can get the AGI first (still waiting on my permanent cert from December...) all that is required is FOI and AGI test results and an 8710 (with only your signature on it).
Don't recall a single balloon or helicopter question on the test, with the exception of one regarding wake turbulance FROM a helicopter being similar to that from a large a/c.
As an aside, anyone actually have a BGI? Doesn't seem to be much point to that, as you are presumably already studying for the CFI test and the information is identical for the AGI (with all of 12 extra questions for the AGI test bank, mostly applying to privileges of the certificate). Plus, though the test is shorter in duration, its no cheaper...
Fly Safe!
PA