"Hoowa" is the SEALs way of saying "yes" or "I agree with you,"
just as the Army says, "Hooah."
The SEALs HQ is not in any particular state or city-- there are
actually two SEAL Team headquarters-- one is at Coronado,
California (the West Coast SEALs) and the other is in Falls Creek,
Virginia (the East Coast SEALs). Coronado is located in the suburbs
of San Diego, Cali, and is where the SEALs are trained. Correct me
if I'm wrong, but I think SEAL Team Six is on the West Coast, and
SEAL Team Four is on the East Coast.
Anyway, the two teams are rivals with each other, everything from
training to how they socialize.
I would recommend a really great book which I bought at MPH. It's
called, "Brave Men, Dark Waters" and it's written by Orr Kelly, who
is an ex-SEAL. It has everything from the earliest beginnings all
the way to to the current, and includes training as well. Mr. Kelly
actually went and interviewed real life SEALs for this book.
Hope all this info helps.