Tommy,
You �ll notice that you have received both answers for your first sentence. That is because both are correct, depending on the meaning you want.
First, I don �t understand the "(convenience)" at the end of the sentence.
Not having a visa can cause inconvenience, and can cause expensive delays.
Not having a visa can cause delays that are inconvenient and expensive.
I would say that "inconvenient" is a slightly better choice, because expensive delays are an inconvenience, so it would be a little strange to single out the delays from the other kinds of inconvenience.
Bruce