Welcome to Tropical Fish Keeping forum.
And welcome to what sometimes (especially in the beginning) seems to be a frustrating hobby...
But the good news is, it doesn't have to be. So let's get your issues resolved.
First thing is that you will learn as you go that some things need immediate action and some don't. Cloudy water in new tanks falls under the latter. This is almost certainly due to a bacterial bloom which is common because the water out of the tap contains loads of organics you can't see, but the bacteria can, and they increase to consume it, hence the white cloudy water. This has to be left alone to naturally clear, and it will, though it can take a few days to even a couple of months. Using any form of clarifier is not advisable. Many act by binding microscopic particles into larger particles that will then more easily be trapped in the filter media; unfortunately these products also bind the gills of fish, not always causing death (though they can) but severe stress which only makes any other issue--like ammonia or nitrite in new tanks--even worse for the fish. At this point, not knowing what that last (brown) product is, I would do a major water change and leave it.
The tank after three weeks may or may not have had a colony of nitrifying bacteria established; the bacterial product you mentioned might have started one. A few small fish and ones that are hardier than some could have worked (depending), but too many and of the wrong type, likely not...as you found out. Gourami are sensitive fish and not first fish for tanks.
At this point I will suggest live plants. Something as simple as floating plants works wonders. Plants need nitrogen, and aquatic plants prefer it as ammonium which comes from ammonia. Live plants will gobble up ammonia like you wouldn't believe, provided there are sufficient plants and not too many fish. We have some plants in our profiles, second tab from the left in the blue bar across the top of the page; if names are used the same in posts they shade and you can click on that for that species profile. Water Sprite is one I highly recommend. Some of the stem plants will grow fine floating. You will need a decent light, we can go into that later.
Another word of advice: don't be quick to dump in more chemicals for this problem or that problem. Stores can be good or bad with respect to their level of knowledge. Sometimes treatments are necessary, but often a major water change will do as much. Every substance that goes into the tank with fish will affect the fish, somewhat. Fish are unique in this respect; most animals live in the air and that remains relative safe and acceptable. But fish are confined to water, and in a very closed space, and water chemistry is very complex. I never add a product to the aquarium unless I absolutely need it, and provided it is safe
The temp at 82 is too high, this causes stress to fish too; oxygen is lower in warmer water, so the fish have to work harder to get it, which wears them down, adding more stress, then any other issue that could otherwise be tolerated becomes a major detriment...you probably get the picture. Around 77F is fine for the average community aquarium. And the fish named will be better at 77F. The corys and tetra especially are having to really struggle at 82F.
So, from all the above, I would do a good water change (half the tank) using a good conditioner, nothing else. The cloudiness will likely persist, but bear with it. You need to clean up that water from the various chemical concoctions, and that will be appreciated by the fish. And lower the temp to 77F partly with the water change and by resetting the heater so it doesn't come on until the water is at 76/77F.
For some background reading to the above, have a look at this article: http://www.tropicalfishkeeping.com/f...quarium-74891/
And...don't give up. This can and will be resolved.