Hi, 

keyboard layout

For that need to have an internet connection to install console-setup. 

1. apt update
2. apt install console-setup
   1. Enter 22 for Other
   2. Enter 43 for German
   3. Enter 9 for German (no dead keys) 
      
      

proxy

Here I found good instructions. Summarized: 

1. cd /etc/profile.d/
2. nano proxy.sh 
3. Add the following text:
   # set proxy config via profile.d - should apply for all users
   # http/https/ftp/no_proxy
   export http_proxy="http://[desired_IP]:8080/"
   export https_proxy="http://[desired_IP]:8080/"
   export ftp_proxy="http://[desired_IP]:8080/"
   export no_proxy="127.0.0.1,localhost"
4. chmod +x /etc/profile.d/proxy.sh
5. source /etc/profile.d/proxy.sh
6. env | grep -i proxy
   1. to check the config

Best regards!