"Support letters" from family/friends were translated by us and the Dutch copy was attached to the translated English copy, both the Dutch and English was signed by who wrote the letter and we copied from our Dutch friends/family their identity cards and attached those to the letter as well. Just so Visa Office Paris would see we are not making support letters ourselves.
We did not translate rent agreements, but highlighted the dates and price.
In case you mean by Dutch, Belgian and not Holland;
As far as the criminal record check paper(no idea how else to call it?!). You can ask that in French
(oh the joys of both countries having English and French as official languages) and you'll have it within a few days. You email, they send a paper copy in the mail. I can look up the email address of the person I emailed about this if you'd like. Doesn't cost you anything.
In Belgium you can also get an international birth certificate. Just ask at the town council. This is also free.
As a matter of fact, I did not pay for any translation or documents in Belgium.
Also something I did ... I went to the town council/gemeentehuis and let them validate a lot of copies for me. Examples; copy of passport, copy of birth certificate, copy of proof of nationality, copy of degree, copy of identity card, copy of drivers license, copy of criminal record, ... Even the things I didn't really need, it looks so much better with an official stamp and autograph on it
I had (and still have) a ton of copies from everything possible, they knew me after a while at the town council lol. All for free of course