For a student in germany, the biggest effect of owning property is on student financial support that you may or may not get:
BAFöG (education benefits provided by the state) will take that property into account. Exemption limits on personal property are very low, so it will make a difference if you own it or if your parents own it.
many Studentenwohnheime (...
The thing that jumps out as the most risky is the bit about "co-owning" the house. This is generally a very bad idea unless you are married to the co-owner living in the house with a close family member. Don't co-sign for a house loan with a boyfriend/girlfriend/roommate/friend, etc. It could destroy your credit and your relationship with them
Your net salary depends on many factors, first which tax class you are categorised, for example if you are single most likely you will be in tax class I. If you get married you can choose between lll/IV and IV/lV. This gross-net salary calculator gives you the would be salary for all the tax classes.