Is my shop sending some informations to PrestaShop without my knowledge?

Unfortunately yes. But those data is only for demographic statistic. Here is the document from Prestashop official team, in which is described sending data process.

Communication between PrestaShop.com and shops using PrestaShop’s software

In order to stay up-to-date on developments with our software and continue to improve it, PrestaShop requires certain useful information. This process is completely anonymous and can be classified into three categories:
Automatic – PrestaShop receives basic information on the number of active stores, installed versions, domain names and the countries in which the software is used. These are used only for demographic data to help the PrestaShop team better understand the needs of the user community (e.g. number of shops using version 1.4, new countries using the software, etc.).
Semi-Automatic – During installation, PrestaShop pre-enables certain modules frequently requested by the community, such as Paypal and other shipping modules. At that time, you are given the option whether or not to accept the installation of these native features. If you do install them, our system sends you a single welcome email with advice on how to best use these modules to start selling online.
Manual – These are only activated by your actions when it comes to manually updating your store, such as currencies, location packs and language packs. It is your responsibility as a PrestaShop merchant to choose whether or not to perform these updates and submit additional information to PrestaShop.com
No personal information about you or your website is ever sent to PrestaShop, and by no means does PrestaShop ever have access to your catalog, customer base, turnover, statistics or the source code for your website. The anonymous connection between PrestaShop.com and your store is only intended to provide the necessary data for the PrestaShop team to help us always improve our product, and to make changes to our software according to the expectations of the community.

source: official prestashop website