Powerplay seems weird since it has been left as a completely pointless, broken mess of a grind.
And I'm not sure anyone even bothers anymore.
Only reason to be in powerplay is because you want one of the special modules on offer.
The way to do that is to stay in for the necessary time, and just before that is checked off, you grind up some merits and get the thing.
Buy a load of them, store them, never use them.
Only thing I would really even consider would be the prismatics shields, and they are too heavy, take too much power, and charge way to slowly.
Got a bunch, never used them.
I prefer bi-weaves.
They had a slight usefulness before there was engineering, but these days you are better focusing on that and ignoring the broken pile of festering shit that is powerplay.
As for the fed\emp ranks just keep doing missions with the rep+ moniker and the decal for each faction and you will eventually get there.
If you must find the quickest route, just google it.
I'm sure there is a detailed youtube on how to get the rank in two days or less.
Following that will get you the thing fast, but it will be soul destroying, and make the actual acquisition seems less like a get.
And for the larger vessels, they need a MEGA-SHIT-TON of engineering to be great, and a lot to be good.
Core mods and guns is a bare minimum.
Hey I'm Thor -
People call me Bob.
Rule 1: Pillage. Then burn.
Rule 2: No such thing as overkill, as long as there are reloads.