1.) As you are aware I did read the OP and don't wish to start with any unfair advantages. On the other hand I am a thinker and like to use technology in a savvy way which is plausible yet not your standard faire.

2.) I don't wish to change the single system rule. Rather the opposite. I know the Luxons are fine but I need more past adversaries to make my backstory work. The prates/raiders would have been a civilization whose homeworld got destroyed in the Kilonova Disaster. They would be reoccouring opponents in the past until the Morte pushed them out of the system. After that their fate could remain uncertain. If you don't wish  to deal with them, just pretend they went away somewhere and never be heard of again. Writing a story has many conveniences.

3.) Where would it improve from here? Only the sky is the limit. There are so many applications for sci-fi technology fields that we can list it all day. I agree that gravity manipulation is versatile but that's what you get with broad definitions. Regardless that's what you get when FTL is involved since spatial manipulation goes in hand with gravity. That and without some artificial gravity tech things could get really strange. Anyways, as I said my only objection is with artifical gravity not allowing gravity based accelerators like my Grailguns. I don't mind the grav lances since they are indeed OP for now (it's also a show what you can do with improved gravity tech). Also gravity-based shields are quite a bit more basic than the typical sci-fi energy shields. These are the reasons why I am surprised you don't wish to allow them. That's almost like banning guns while nuclear ICBMs are allowed.

4.) I do recognize your authority in this game and that's why I wish to discuss things. If you feel this is an attack then there's something wrong in our communication. On the other hand GMs using their position of power instead talking things out is a good way of chasing me away. In that case you'd be right I signed up for the wrong game.

5.) I repeat, I don't wish to make my nation too powerful, either. A few tech which I noted are overboard already and I work on to balance them out. On the other hand I don't agree with your assessment on certain advancements which is why I am trying to continue the disxussion.
Battlestar Galactica, huh? They are pretty hard to rank in tech but generally they are considered on par with Mass Effect sans the numbers.
Personally the thing I had in mind is Legend of the Galactic Heroes.