Within 15 days of making the account, to add. If you missed it or decided you'd rather not give them the password to your previous email account (the alt objective for the Gmail-specific thing) you don't get a second chance.
I get that it's free but I trust them much less because of the way they handle that.
For the port thing, you can set the
net.ipv4.ip_unprivileged_port_start
sysctl to a lower value like 80 (may need to go lower if you also do email). It also applies to IPv6.The default of 1024 is for security, but the actual security granted by it is not really that relevant nowadays. It stems from a time where ports < 1024 were used by machines to trust other machines using stuff like rsh & telnet, and before we considered man-in-the-middle attacks to be practical and relevant. Around the start of this millennium, we learned better. Nowadays we use SSH and everything is encrypted & authenticated.
The only particularly relevant risk is that if you lower it enough to also include SSH's default port 22, some rogue process at startup might make a fake SSH server. That would come along with the scary version of the "host key changed" banner so the risk is not that high. Not very relevant if you're following proper SSH security practices.