I'm getting an "Alliance/GDI" expense on my Advisor page.

It clearly says on the GDI Page that, "On this server, GDI is free and required".

The Global Defense Initiative (GDI) is an open organization dedicated to the protection of our members. As a member of GDI, you will receive the protection of GDI forces. No country more than twice your size or less than half your size will be able to go to attack you without first formally declaring war. On this server, GDI protection is free and required.

It's required but not free despite what it says. You can use the bonus to get rid of it.

Everyone is in the same boat tho. Im not sure I have ever done the free GDI on tournament. Have not done the math on it either tho.

Turns/booms are way better imho on account of them being way more potent than on other servers

I always take the free GDI points, just seemed a good thing to do at the start when a few turns didn't seem to matter. I like teching as well, so the booms don't help..or do they?

no booms help techers (well money booms help and indy booms help but marginally).