embassies
The Vietnamese consulate on Ekareach Street issues 30 day tourist visas on the same day the application is submitted - sometimes while you wait. As of December 2011, the cost was US$27 for Cambodians, US$45 for foreigners. The opening times are 8AM-noon and 2PM to 4PM, M-F, 8AM-noon on Saturday.
internet
There are many internet cafes and some guesthouses and many hotels offer internet access. Many now have wi-fi - some for free.
post
The new main Post Office is near the Victory Park on the left hand side of the road as you go to Victory Hill. There is also a branch at the market downtown, but here you can only leave your postcards during office hours, as it does not feature an outdoor mailbox.
contact
Sihanoukville's area code is 034.