Hi Julie,
What do you mean by professional and culture codes?
Are you a Slovak speaker?
For me its like any job interview, you have to match what the employer requires for the role. For me I've only applied for jobs where they require English so for me it was just a normal interview process. Learning Slovak now.
I usually wore a suit and a tie aswell.
All you need to do is just be professional and natural, and most importantly speak a little Slovak, for example use some Slovak expressions like dobre, nech sa paci, dobre den etc. So that way building rapport is much easier. 
Hope this helps,
Jamie