2] How to access your server using SSH?
If you have IPv6 connectivity simply use your assigned IPv6 and port 22 for SSH.
OR
For SSH over IPv4
Shared (NAT) IPv4 - y.y.y.y
Internal IP - 10.37.130.xxx
SSH using - y.y.y.y port xxx21
You need an SSH client to access your server, use PUTTY (https://putty.org) it's free.
3] Which IPv4 ports can I use / I did'nt understand how to SSH?
You have been assigned a range of 20 ports on your Shared (NAT) IPv4 address and 1 extra forwarded port for SSH.
The first 20 ports are based on the last octet of your internal IP, you can use these for anything you want, examples below:
example: 10.37.130.100 has the following port range usable: 10001-10020
example: 10.10.10.221 has the following port range forwarded: 22101 - 22120