FO is undergoing a massive revamp right now and many aspects of the game has been changed or will be changed. This is why the AI is passive - the new stuff hasn't been implemented to the AI yet.
When you drag one of more ships from a fleet to the "New Fleet" icon, the game crashes. I tried it multiple times, it crashes each time.
I've had this problem too ever since I started with FO, but it hasn't been a major setback in FO's development so far. I think it will be a while before this gets fixed.
When I started the game, all the fighter ships (mark I to IV) immediately were labelled with a red X (as if it was an obsolete design).
Furthermore, the basic medium hull option was missing. This might be the cause of things. (Several turns later, the basic medium hull option reappeared, so I could create new ship designs with it. When I did, there was no longer a red cross when I created them).
As I was still able to build the ships, I did not really bother to report it.
The Mark series pre-designs originally had a unique icon that later got removed. The red X is a temporary substitute. The medium hull shouldn't be missing though. I've never had this happen to me yet.
I'm not able to colonize worlds with the "Solid Core" special, not with a colony ship nor with an outpost ship. Maybe this was intended.
The special lowers the max population as of this SVN. Try researching some techs that boost population or colonize that planet with a phototrophic species (such as laenfa).
I have not been able to invade home worlds of AI races. Even though I have a large fleet present and lots of troop ships. The invade option simply does not appear. Also, the planet picture is also "faded" with horizontal black lines. Maybe this was intended.
I have only found one colony created by an AI race: I have been able to invade this world succesfully, so the invade option is working.
For the record, when I tried to invade AI home worlds, a battle occurs each round my fleet is present in that system. But I haven't been able to notice any results.
This has something to do with the stealth of the planet. Enemy homeworlds also give a massive stealth boost to their ships, which is why you can't really tell what's going on. Maybe it's something the programmers added in for this SVN to give the AI some ability to resist capture. If you check out your homeworld's stealth stat occasionally, you'll see that it's off the charts (along the lines of 1k+). Pretty much the only thing you can do is to research sensors and try to decrease the stealth of the planet you're trying to invade somehow.
When building one 'terraforming' building, it does not necessarily improve the environment by one step to the preferred environment (as suggested by the research description of both 'Terraforming' and of the building 'Terraforming'). In reality it takes about 3 terraforming buildings for 2 steps. This also varies (as far as I can see it is dependend on planet size)
Unless terraforming has been changed, this should be right: Most species have 4 hostile planet environments. For example, barren, radiated, inferno, and toxic are all hostile to humans. In this case, radiated and inferno are "extra hostile". Say you terraformed a radiated planet, it will turn into a barren one, but barren is still hostile. Check this out. It should help: http://www.freeorion.org/index.php/File:EP_wheel.png
Another odd thing was that I was not able to use 'Terraforming' on a hostile planet environment. It stated that the population requirement was not met. After I researched 'Xenological Hybridization' I was able to terraform these worlds. (I'm playing Terran, so in this case it were barren and radiated worlds that I tried to terraform.)
Terraforming only works on planets with a max population of at least 1. If you want to terraform planets with a max population of less than 1, you'll need to research remote terraforming and use that instead.
I agree with you and Zireael about the production tab thing.