Which information is stored in European Passports other than what is written in it?

In additon to information printed on the passport document the chip stores

• a face image in digital form (although it is the same image that is printed on the passport, its quality isn't affected by reflections, degradation over the years, dirt... therefore you could consider it as "other" information)
• in most cases fingerprint data, and maybe other biometrical data (depending on the country)
• last, not least, a digital signature over all digital data stored on the chip, issued by the country that issued the passport.
  This makes the data much more trustworthy than relying on the optical security features of a passport document.
  Anybody (not only the issuing country) can verify this digital signature.

By the way: the specification European and any other passports comply to is not a secret and it is publicly available (in six different laguages!): ICAO Doc9303; note that only a small fraction of what is specified there, gets actually implemented (e.g. no address in German passports; although the specification describes it).
Also reading and verifying most of the digitally stored data (not the biometric data though) of a passport can be done by anyone having the right tools (NFC reader or NFC-capable mobile and the right software; no special legitimation required).
This is not the case, however, in general for ID cards (e.g. German ID card).

Now concerning the data examples you mentioned:

• "information about everytime I travelled abroad with my passport...": no, not stored
• "marital status": no, not stored
• "home address": could be stored; but then I'd expect it also to be printed on the document; e.g. German passports don't store holders home address; if you are required in your country to bring your passport when you register a new home address, then probably yes.

Which information is stored in European Passports other than what is written in it?

In French passports, until 2008 the chip didn't contain any other information on the passport holder, then in 2008 the law changed and fingerprints of two fingers were added. Note that the chip does include a digital version of the photo printed on the passport.

Source: Décret [archive] no 2005-1726 du 30 décembre 2005 relatif aux passeports électroniques. See Article 2 quoted below:

Article 2: Afin de faciliter l'authentification du détenteur des passeports mentionnés à l'article 1er, ces titres comportent un composant électronique contenant les données mentionnées au même article, à l'exception de la signature. Ce composant électronique, qui est une puce sans contact, comporte des sécurités de nature à prémunir le titulaire du titre contre les risques d'intrusion, de détournement et de modification.

Modification from Décret n°2008-426 du 30 avril 2008 - art. 3 (mirror) (thanks jcaron for pointing it), which adds fingerprints of two fingers:

Afin de faciliter l'authentification du détenteur des passeports mentionnés à l'article 1er, ces titres comportent un composant électronique contenant les données mentionnées au même article, à l'exception de la signature, ainsi que, hors le cas prévu au premier alinéa de l'article 6-1, l'image numérisée des empreintes digitales de deux doigts.

With high probability, it contains exactly what is written on the hard plastic card, nothing more.
How would that other information even get there? The chip is read-only, so you would need a new passport every time they want to store that you travelled.

In addition to the information which is also written as human-readable text and the facial image that is printed in the passport, the chip also contains biometric data such as fingerprints (one exception is for passports issued by Ireland, which do not contain fingerprints). See https://en.wikipedia.org/wiki/Biometric_passport#European_Union_/_EFTA for details.

The information regarding travels abroad is not stored on the chip (but it may exist in some government database and could be retrieved by the authorities, when needed).