you can say don't mention it or most appreciated
ni hao (Chinese)
"Tervetuloa [PLACE]+[END]." Enter the name of the place to the [PLACE]. But the [END] is very difficult to foreigners. You have to say the right kind of syllable at the end. These are combined...
welcome abourd or welcome onboard is both good because the both make sence
No, You should say "Your Welcome"