I do advise you to have your recommenders fill out a different letter for each school, so that your recommendations are customized. A generic letter that you apply across all schools is not recommended. Yes, this is more work for your recommenders. However, you (and they) should know that a lot of the answers are recyclable, so the first recommendation will be the most difficult and it will become progressively less work.

You can also help your recommenders by supplying them with useful information. I posted some guidelines for guiding your recommenders on my blog, which may be helpful:
https://blog.stacyblackman.com/2005/08/0 ... ommenders/

Finally, another option is asking a few different people to write your recommendations. You may ask one person to write letters for three schools, and another person to write another three. Depending on your options, this may be a good approach.

A professional translation service is a good approach, as it will allow the rec to be more polished, professional and expressive. For a school like HBS, I would say it is a necessity. For most other schools there is a bit more flexibility, but it certainly cannot hurt.