The arifact costs seem fine to me. We could have turned them on and won, but we decided it would be more fun to conquer Throne instead.
Wormholes shouldn't be rushable instantly, since it makes destroying them in battles almost useless.
The higher max IP played well, it slowed down the game. It also made structures a lot less powerful. Dropships had to be used a lot more sparingly, I. Wormholes were noticably less effective. It made homeworls a lot harder to conquer though, which I think is a good thing. (with 123 IP you need 2 perfect battles with 50 dropships (35IP+50IP-25IP=60IP, not enough) to get a homeworld instead of 1)
You probably should have 100 IP for most planets, and more for some special planets.
The current attack signup system is really bad. It shows a shiny attack planet button on the top which nabs will inevitably press, attacking the wrong planet with the wrong people which screwes over the faction. There is also an issue that lots of people will see a defend button, lots will quickly click it and it will turn into a attack planet button which they didn't want to press and they will attack the wrong planet. Sounds unlikely, but it already happened to me.
The current system also makes nabs discouraged from playing.
I see the new system and it fixes most of the issues. I am kinda sceptical about the launch multiple invasions on 1 planet though. Do you really want to have 7 invasions at once on your homeworld? That makes defending it pointless. Without the ability to attack the same planet you can have bad players attacking some backwater planets and it will make them useful. Also, when defending if there are 7 invasions on your planet, you don't know where to put your good players-with one invasion per planet you can have an self-balancing system where pros get or defend the good planets and bad players get/defend the less important ones. This might actually lead to having balanced battles in PW.