Item upgrades are confusing, Engine of innovation, Catalyst console

So from what I can tell these are systems to upgrade gear to gear I do not not have I guess. The in game explanations of these systems do not seem to exist.

My main question is how do I obtain more sparks of ingenuity, and what exactly dose the engine of innovation do? what kind of gear dose it upgrade? and what dose it upgrade to?

And the same goes for the catalyst console and catalyst charges. How do I get more charges and what is the significance of the gear it upgrades to?

There seems to another third bear upgrade path, elemental overflow system. That seems pretty straight forward. I think I understand that one except how do I get the purple books to upgrade to the final level?

Am I missing any other gear upgrade paths or currencies ect?

I don’t understand this either. I am really bewildered. I saw my characters were level squeezed but it didn’t seem to translate to the gear at all, so even though I left with a raid grade character at the level before, the gear is almost worthless now comparatively and Im not sure what else to do to improve it. I didn’t even know that you could until I put an item on the auction house to check it out and saw that there are these wildly different ilevels of the same thing?

If I were you I would just start doing the beginning quests on the dragon isle. As you do them you will start getting 359 gear. But first you need to get you character up to lvl 60-70.
Pick a past expansion and work through it to lvl you character.

Once you have at least one character on an account at level 50, you can level any character using “Chromie Time” from level 10 to 50. Mobs, XP, drops, and rewards will scacle with whatever your level is.

Cata is an exception as it requires flying which isn’t available until level 30, even with chromie time.

Hovering your mouse over a zone on your map will show the level range within the zone without using Chromie Time. Stuff in zones you have not activated Chromie time for, will not scale with your level.

Pandaria has several gear vendors that cann outfit you for 5-10 g per piece. I don’t recall if they cap at level 35 or scale all the way to 50 in Chromie time.

I have not bought the expansion. I just went through a whole thing locating and accessing my account, and logged into a low level character to see significant UI changes so I thought they had addressed important things. I subbed to try playing again since Ive been gone a little over a decade, but sadly I found they had not addressed things like addons and all that. I am playing in the dark, just like that. I will continue to play and but that was a big blow. I regret the re-sub.