SSL SHA-256 / TLS 1.2- & HTTP/1.1

Centos 6 & Plesk 12.5 with latest updates

Hello, I've got a few clients using PayPal and they got a message from PayPal saying they need to update 2 things to keep using PayPal.

How can I upgrade the SSL Certificates to SHA-256, TLS to 1.2 and HTTP/1.1.?
And is it a good idea to upgrade TLS and HTTP to the latest version or not?

Thanks in advance