Glad you’re considering Vilnius. It’s generally a very safe and welcoming to foreigners city. One thing I would suggest is avoid living in the neighbourhoods around the airport (mainly ‘Naujininkai’), as those are a bit less prone to crime. If you’re not planning to relocate here permanently, English language will be enough to communicate pretty much anywhere. There are plenty of jobs that are English only (I’d say mostly in IT companies) and a lot of them offer part time positions. Hope this answers your questions.