Flt pay at CX
 

Do you get Base + Flt Pay + meal allowance or is it strictly salary?

Yup Salary + Flight Pay
Allowances are paid upon arrival at the hotel in local currency, and it varies from port to port. So at least you don't have to dif into your own pocket and wait until the end of the month to recoup.
Allowances are usually enough to eat, buy some stuff and still come home with a little in your pocket again depending on the port some more than others.

what is the flt pay

I think FLT pay depends on ya destination..... or is that meal allowance?

Aussie

So is the HDP in lieu of a per diem?

No, in addition!
You receive:
1.) Salary
2.) HDP
3.) Meal allowance (paid in cash at your layover hotel)
Cheers