How to migrate all data to the new or latest 7.11.x?
welcome to community.
First you should backup all your files and data to keep a working copy.
From the Upgrades available, first run Upgrade Wizard for 7.8.x-to-7.10.33.zip
Next step is to Jump from 7.10.x-to-7.11.22.zip
That will land you on the latest version.
Do I need to do something with the system requirements?
What if the leads whatever attached to like opportunities module and etc?
If you are running SuiteCRM 7.8 with PHP 5.6, then you can do all the upgrades as 7.11 still does support php 5.6
Your data/modules/relationships will remain intact. After each upgrade, do run System Repair/Rebuild and make sure its stable before jumping to next upgrade.
If I upload the data(leads,etc) instead to the latest version?
Anyway, I just extract all the leads,opportunities, etc from the old version and upload it to a fresh installed latest version?