I think that is what is going to happen. Should make things interesting.

From what I have observed planets that require no improvement techs, can be colonised by all races. Any planet that requires e.g. toxic improvement is required by all races to colonise. I could be wrong. Also some planets can not be colonised no matter how much tech you research.

In addition, I think the Iconians can colonize Toxic and Aquatic worlds, unless their ability has changed without notice.

I love this new option in the game, the different planetary types. Not only does it give more interesting variety to the beginning of the game(no more planet rush, or atleast a more strategic drawn out one), but it also gives you more interesting planet graphics. Like the aquatic worlds, even though youve researched that tech and you can colonize those planets..youre still building on water, there arent any land masses. And the cloud cover over the planets, how it rotates above the rotation of the planet..very cool. Ok, last thing....i LOVE zooming into a planet and watching a new ship i designed rotating in orbit around the planet...AND correctly scaled!

To answer the main question, there is a good variety of habitable worlds before the planet techs. Its the same random generator as before, where depending on which part of the galaxy each race is initially placed and how many stars in the vicinity determines how many planets you might get. I will say though that they added habitable planets at level 1, however it seems like the AI ignores these because ive come across them half way through a game on the other side of the galaxy...makes for a good outpost.
Also, as per the races listed above starting out with the planetary techs....i believe the yor and iconians are correct, but i dont think the torians have the aquatic worlds. im not sure on that one though...

I would like to know if the environment techs will be more spread out and less linear in the final version. I do not have the beta, but from what I read, the environment techs are linear like the other techs. From the previews I read, I thought they would be spread out to avoid rushing the environment techs.