As I have already mentioned in several other questions, graded readers are a good resources for extensive reading, at least for people who are not yet sufficiently proficient to read texts written for native speakers of the target language.
Are there any graded readers for Dutch?
The German publisher Compact has published a few graded readers for Dutch in their series of Lernkrimis ("crime stories for learning"). These books have a CD with MP3 recordings of the text; they also contain exercises:
Kees Van den End has published several books in the series "Interlinear Dutch to English". These books contain an English translation of the Dutch on alternating lines (with the English in smaller print) instead of the facing page. There is no audio version and there are no exercises. Below are a few titles (available both in print and in Kindle format):
Note: Not every book with "reader" in the title is a graded reader. For example, The Routledge Intermediate Dutch Reader by Eddy Verbaan et al (Routledge, 2013). The goal of the Routledge Modern Language Readers series is to increase reading comprehension skills; each text has a vocabulary list.
Yes there are and I'd recommend just using the lists that are used for (older) children. As you might have guessed, the market for second language Dutch learners isn't that big, but there are many people who write children's books. Because of that, new books get published a lot and as such they are more relevant when it comes to new trends.
I cannot find a complete list for primary school level, if you do want to read into that, I suggest searching for the term AVI, which stands for Analyse van Individualiseringsvormen (Analysis of Individualising), and it's the main thing used in Dutch primary schools. There's a bit of info on it here, specifically the colour table after a bit of scrolling indicates when one should be at what reading level in the primary school system. Pupils start in groep 3 aged around 6-ish and end in groep 8 around age 12, so that should help put the table into perspective.
The main part of my answer is based on lezenvoordelijst.nl which is a list compiled on a national level. There are actually two lists, for ages 12 to 15 and for ages 15 to 18. Each of those links explain the levels within those lists, instapniveau and niveau 1 being the lowest level and going up in number the harder levels.
My links actually link to the teacher's section of the website, so for each title there's a link Docentinformatie which gives some background on the title giving the teacher the opportunity to give their students some more information (note that it does include spoilers, those are mentioned explicitly though, but all in Dutch).
As a language learner, I think it's best to start with the lowest level for the 12-15-year-olds. I've scrolled through those a bit and think some of them are really aimed at little kids, whereas others might be interesting for adults as well:
Ontsnapt aan de Taliban, fiction about a terrorist attack in Afghanistan.
Het leven van een loser 1: Logboek van Bram Botermans nonfiction which seems to be a translation of Diary of a Wimpy Kid.
Vrienden voor het leven, nonfiction story about a French businessman who became paralysed.
Uitgehuwelijkt, fiction about an arranged marriage.
Ik overleefde Auschwitz, nonfiction about Auschwitz survivor Ferenc Göndör (in Swedish).
