Vietnam Visa in Siem Reap and travel agent

[Kiara]

Hi there- thanks in advance for replies - a couple of questions
1. Need visas for vietnam - all australian - 2 adults and 2 kids under 11. Differing advice...do I do the online visa letter thing for all 4, then at Danang airport pay for all 4 or are kids free? Do they still need passport photos? My apologies for asking when this appears a lot in these forums- the answers differ wildly...
2. In planning misread the cost of flight from REP to DAD (danang) - oops (thought it was in VND but in fact was in KHR- derr) - so this flight is $200 USD PER PERSON from vietnam airlines direct. Wondering if booking it when we arrive in cambodia will be cheaper?? If so please recommend a travel agent in siem reap!
3. We have 4 days in Siem Reap (staying at sofitel) in early january - kids are 10 and 9...advice re a basic itinerary appreciated....

[Karic]

1. Yes, you have to bring 2 passport photos each person. If you do not have it, they can scan photo in your passport but your are charged for that service. You know price for services at all airports, very high.
2. Not cheaper, you should book directly in Vietnamairline website.
3. 4 days is enough for classic tour in Siem Reap, travel desk at your hotel will help with some options.