dalat
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Currency is Vietnamese dong. Dollars are also often accepted. Plenty of ATMs in towns for getting VND.
Ho Chi Minh City is not especially great for birding, you may get some birds in the zoo or road-side trees, but nothing you won't get in Cat Tien or elsewhere.
With a free day in HCMC, I'd do a day trip to Can Gio to look for waders and other water birds, including (possibly) Spoon-billed Sandpiper and Normann's Greenshank. Unfortunately I've never been there, so can't give detailed advice. The HCMC based birding companies can certainly arrange a day trip (http://www.vietnambirding.com/ or http://www.vietnamwildtour.com).
Ho Chi Minh City is not especially great for birding, you may get some birds in the zoo or road-side trees, but nothing you won't get in Cat Tien or elsewhere.
With a free day in HCMC, I'd do a day trip to Can Gio to look for waders and other water birds, including (possibly) Spoon-billed Sandpiper and Normann's Greenshank. Unfortunately I've never been there, so can't give detailed advice. The HCMC based birding companies can certainly arrange a day trip (http://www.vietnambirding.com/ or http://www.vietnamwildtour.com).