Pricey new colonies

It depends on the PQ. Low PQ planets cost money to maintain (PQ < 13): You need artificial air, living facilities etc. for your settlers.
High PQ planets actually give you money even at 0 pop.

How have you determined this value? Setting the spend rate to 0% and watching how much you spend on the planet?

I used my first colony ship on a PQ 16 planet, and the next turn the cost was 6B while it was taking in 3B.

Does it also depend on starting pop? If I colonize with 25M, will I have a "profitable" colony from the start?

You are likely running on 100% spending. A planet on 100% quite often costs more than it provides. That is the reason you can get trade routes.

Contrary to other 4x games (like civilization), spending aren't related to income. So you can spend more than what you earn. The tax rate has an influence on the tax income from each planet. The spending rate is how you utilize the capacities of your planets. So it is normal at the beginning of the game to spend more than what you earn. After all, you have 1000 BC in the treasury.

Is there a way to adjust individual planet spending?

Nope, the idea of the game is to syay 'big picture'. This aspect has drawn a lot of criticism and I'd like to see GC2 address it in some fashion without forcing us to micromanage each and every planet. Some sort of 2/3rds return on wasted spending or something so it feels more intuitive to a game player.

What I would like to see is a way to have spending reduced for "new" colonies.

Well, the reason behind the empire wide scaling is so that this game doesn't get you bogged down with micromanagement. If I want that, I'll go play CivIII again. Keeping it a bigger level lets you focus on killing everyone else that is sentient, not economics. :evilgrin:

Why would you want that? Spending is only a function of planet capacity anyhow. Your PQ 34 with every power plant and 4 +70% starbases nearby can produce a lot more, it costs a lot more. The new colony with nothing costs very little.

What you want is to spend more on new colonies and less on old colonies since they're usually not building anything.

Well nut much chance of having 4 SBs in the same sector as the game is right now. 4 SBs costs at a minimum 0+200+400+600=1200 BC If you have 4 resources it's 800+1000+1200+1400=4400 bc, not counting the cost of building the constructors.

When I build a new SB now it costs 600BC, but it says "Logistics = 0". Does this # mean there a tech or something I can build to reduce the price?

Yes, there are three logistics techs. The first comes from industrial theory, then base logistics. I don't know about the others because I never bother with them. Never build starbases at all.