If you want the visa, you will ensure you translate all the documents you plan on presenting which are not in English, regardless of the cost, especially in your case which looks like you're interviewing in a country outside of which the documents were issued.
And why would you need to translate the medical exam? The medical exam is supposed to be done in the country where the interview will be taking place, the panel doctor already knows which language to use in completing the medical report.
Frankly speaking, if the cost of translating your documents is such a big deal to you, you really should reconsider the wisdom in wanting to immigrate to the US. You will start spending money almost from your day one in the US, and most likely long before you start earning an income.
By the way, I hope you're aware the $330/person visa fee is none refundable. And that the GC fee you'll need to pay has gone up from $165/person to $220/person. Not trying to scare you with all these, just trying to make sure you're aware of what you're getting into.