Hello and welcome, and thanks for starting a new thread, I think you'll get a lot more responses this way.
As I had mentioned to you earlier, reading the profiles for these fish will give you all the information you need to determine what will work with what, and what type of water they need. If you type their name in your posts, they'll be highlighed blue (like you see below) which you can click on to view their profile.
As was already mentioned, live bearers, which are fish who give live birth rather than lay eggs, require hard water. In your list, these are the Guppy, Platy, Common Molly, and Swordtail. All of the other fish on your list are soft water fish. So in general, these fish should not be kept together as they have different water requirements. If your water is in the middle, it's possible to fall into the range of both for some of the fish but the soft water fish really do better (live longer lives) in really soft water and livebearers do best in fairly hard water.
The Blue Ram is a warm water fish, and should be in a tank 80-86 degrees with the middle of that range being best. That is warmer than most fish like. To keep two of these, you must have a male/female mated pair, and they must be a pair when you buy them. You can not expect a male to accept any female, he has to decide.
Dwarf Gourami are similar in that you could only have one male. A sexed pair is best. They also can be aggressive to brightly colored fish.
Scalare Angelfish, which is what you'll find in most pet stores, are a slow sedate fish and should not be kept with anything that's very active. They should not be kept with Gourami. Another note is these are a schooling fish and need a minimum of 4 of them with 5 or 6 being better. A 30 gallon is far too small for four of these fish, they get large. The only way they can work is if you get a mated pair (again, they must already be a mated pair).
As has been mentioned already knowing the hardness of your water (in numbers, 'hard' and 'soft' can mean different things to different people) will dictate what fish you should keep. You can go to your towns water department's website and read the quality report. It is usually included in there. If not, take a sample of water to a pet store and ask them to test it. Be sure to write down the number to share.
Last edited by Geomancer; 12-07-2012 at 08:29 AM..