As someone who has actually been running a business that operates internationally for many years now allow me to pass on one of the most vital points to you.
You really do need to use professional tranlsation services. No, you cannot get by just hiring a combination girlfriend/bilingual secretary. It really is important that you get major and important documents properly checked over, have a proper professional translation done.
This is obviously important for contracts: if you're not absolutely certain of what is in a contract then you shouldn't be signing it. And if the translation isn't perfect then you won't be catching the nuance of what is in the contract.
You also need a translation service when you're looking at offers: so much of the problem that we all have with other languages is over tenses. It makes really a rather large difference if you've got to pay people before they do anything or whether you have to pay them after they've done something.
So, if you're going to be doing business internationally then really, take my word for it, a lesson that I've learned very expensively. You really do want to use language translation services. Yes, you really do want to pay for them.