I used to get 10 CPU per captcha solving, now its just 7.
Is this a bug or intentional feature?
It's intentional. See
https://bitcointalk.org/index.php?topic=1261310.msg13504099#msg13504099 and
http://www.satoshigalaxy.xyz/help/faq#my-cpu-rate-is-going-down-why for a better explanation.
Now for the admins

Im unsure how to claim a planet. Errors it gave state that it is unpopulated, so first thought i needed to find a class M or build a biosphere. Well, found a class M. tried again, said unpolulated. so I tried to spend 5000 satoshi for population. It said I couldnt do that beause it was unpopulated. How am I supposed to populate it if I get no population errors when I attempt to populate it?
You're on the right track! The last missing piece of puzzle is getting initial colonists (by recruiting) from an already occupied planet.
We're writing a manual (a player volunteered to help us),
http://www.satoshigalaxy.xyz/help/manual#colonization but it's not too useful in it's current state.
While we're on the topic of planets, can I build a quarry on a planet without building other stuff (like biodome and warehouse) first? Can I build a quarry even with zero population on the planet?
You can, but it won't be too useful. Best case scenario you'll have a usable quarry once you colonize. Worst case scenario someone else colonizes that planet and gets a quarry for free.
Bug: Redirection from broadcasting message
Whenever I broadcast a message, I get redirected to the main Sector/Station/Planet page (depending on whether I've docked/landed or not).
Doesn't matter if I'm on the Ship/Profile/Map/Marketplace page or just approached an asteroid/ship, I get redirected all the same.
Filed, thank you!
But then again, I've never seen any chatroom/shoutbox that reloads an entire page when you type something...
Nor should you see anything like that again! In today's update, we've finally AJAX'ified the chat.