I've been reading on the wiki and other user posts, and it seems like people go back and forth about whether these artifacts cause a planet to be invincible. It allows free colonization - which I imagine will be more useful when I have more planets, but is the planet they are used on now invincible?

No. They just do not count toward your planet limit.

but it is better to create invincble with a drannik one instead of a regular one

at least for as long as u are still short of planet spots(a problem ppl under 400-600 might possibly encouter, not so much of a problem for ppl above that XD)

because should you lose the drannik one, you also lose the "spot" it came with, which means you will end up with 1 fewer total planets in term of limit
so ppl perfer to not lose it~

but no, the colony ship itself does not provide this benefit

If you take a drannik one, do you get an extra planet slot?

not exactly

drannik come with its own "slot" that only it can use for as long as u have it.
that means it does not count against ur limit as long as it's continously in your procession

but if you lose it and get it back, it will cost a real planet slot, hence its own "unique" spot expires

does that make sense?

Enough that I couldn't have explained it any better...

Yeah that makes sense thanks

Do they count towards the cost of your next planet/invasion?

One important note that some people may want to keep in mind.... If you happen to scan an unoccupied invincible (due to the original's owner's inactivity causing their account's deletion), the colony ships are the ONLY way to colonize those planets

It is said here:http://galaxylegion.com/forum/viewtopic.php?f=3&t=21001
that the colony ship does NOT work on invincbles

I do not know if it really does because i've never tried it myself. But do you have any basis for saying that it does?

Seen it done by a legionmate (he commed that he had found one, mentioned he had a colony ship still, tried it and it worked.

Note: this is only truly useful to those who haven't bothered using or haven't gotten their colony ships yet, with the extra provision that they get lucky enough to find an unoccupied invincible (note that I believe the invincibles should evaporate along with the player owning them, but that's just my opinion).

As i posted in another thread, i already tried this very procedure on an "unoccupied" invincible exotic, and it did not work.

So perhaps its a case that it "did" work in the past, but Dan has likely fixed this now.