If you're installing on a fresh 3.55 OFW console, install the Rebug REX firmware first of all, and if you ever want to convert to DEX (debug) firmware, then use Rebug Toolbox to dump your eid_root_key and use the CEX -> DEX conversion tool.
If you do happen to go ahead and do that, and a Rebug update is released in the future, grab the D-REX firmware PUP from the site instead of the normal REX PUP.
(tl;dr, CEX -> Rebug REX firmware; DEX -> Rebug D-REX firmware)
Be aware you cannot go online or use PSN features on a DEX console/firmware. See below answer.
Regarding installing a different firmware, you aren't stuck with it at all; you can still go ahead and install the other desired firmware if you so wish.
Yes you can go online with dex
In toolbox under eid root key dump there is a setting to use eeid5 this is your idps with normal target not dex target
You have to do this setting every boot
Or use webman to spoof your idps with normal target at boot so it's done for you
You then do the same as CEX
Load a game via webman
Run psn patch to turn off cfw features
Then run your loaded game and go online
Grab the latest Rebug PUP firmware from the Rebug website, place it onto a USB drive at PS3/UPDATE/PS3UPDAT.PUP, then insert the USB into your PS3, and "update through storage" from the system update menu.
Just go to the normal settings menu in the XMB, and choose the system update option and "Update via Storage Media".
Before you update, make sure there is no disc already in your disc drive first and foremost!
Is there a place to learn what all these name means and their purpose in the console ?
or any other useful acronym or names.
I suppose it's related to the uniqueID used by PSN ? but if you edit or hide your uniqueID but still use your own PSN account, can't sony detect it and ban your account? (they probably won't ban the console, but the account is currently used, so they can ban it, right?)
Console ban is very common
Your idps is what is banned
The target Id is the first two didgits starting 8 after all the 0's
The 86 is your target the rest is per console id
To change the idps you need to dump your eid key
This key is different in every console
If you sign the idps with the wrong key then the console cannot read it and the console soft bricks on boot
Psdevwiki is where all public known info on the PlayStation 3 and 4 is made available
Remember to look not only on the main pages but the talk pages as some devs post hints tips keys and sometimes full blown solutions to unlocking parts of the system