many, many questions

1. The jury is still out on this one. In the recommended dosage (1 tbsp/5 gallons I think) it usually doesn't seem to do anything. Higher dosages are good for treating ick. Some people swear aquarium salt is a magic tonic for fish, other people say it's not the best thing for them. However, it's highly unlikely that you'll hurt your fish molly or platies with a normal dose.

2. I suppose it's not really "normal" but I don't think it indicates a problem, either. We used to have a hyperactive molly, too.

3. With proper filtration, an airstone is NOT necessary. The purpose of an airstone (without an UGF) is twofold:
a. it provides surface agitation for better gas exchange across the surface
b. it makes unnatural bubbles that some people think are pretty
A normal hang-on-back filter will provide enough surface agitation. So if you like bubbles, get the airstone, but you'll be perfectly fine without it. I find the bubbles to be kind of noisy, and they require yet another electrical outlet.

4. Normal cleanings shouldn't be too stressful for your fish. Make sure to rinse your hands with water (NO SOAP) really well beforehand so you don't introduce chemicals into the tank.

Rearranging the tank decorations can stress fish because afterwards they have to claim "new" territory (if it is a territorial species). However, if you are introducing a new fish, this is an excellent technique because it lets everyone start over from a blank slate.

1.my only experience with salt was simmilar. it was sold to me for a puffer. he didn't seem to care one way or the other weather he was brackish or fresh. my other fish (chiclids) became sluggish and unhappy. i'm sure salt is ok for some things but don't fix whats not broken. that's to say if the fish are happy without it, don't add it.
2. I've seen fish do this but i'm not sure if I can't say if its "normal"or not.
3. an air stone depends on what setup you have. its used to put oxygen in the water. I've got a small bowl for feeder fish. without the airstone they would die in a few days. when i put the stone in they last till there eaten. In a bigger tank, if you have a good filter system, this should provide enough oxygen for your fish.
4. Make sure your hands are washed and rinsed well before you put them in the tank. the fish might be affraid at first but will get used to you after a while. Try not to startle them too much, move slowly. If you lightly brush against the fish it should be o.k. just don't try to pet them.

4. don't have an airstone if ya want plants.
1. depends on what the other fish are?

Actually, if you have plants an airstone can be good. It should just be part of a CO2 injection system rather than connected to an air pump...

But that's just me being difficult, lol.

1. I went to this family owned fish store that an experienced person (im a newbie to the max) recommended. The ppl had beautiful, healthy fish (as far as i could tell) with well planted (real plants lol) tanks. They had 23 years experience, and they also included "aquarium Salt" when i purchases my gold dust mollies, and they assured me the dosage (2 tsp per 5 g) wouldnt bother my platies-i added it and so far the fish are fine...
2.My gold dust mollies (and platys too) do the same thing! lol theyre just "active" i guess
3. I was wondering the same thing but my hangon aquaclear filter provides enough surface agitation and even a current so i didnt bother with one
4. Ive done it to add a fake plant and thyre were no probs-the fish r pretty fast theyll dodge ur hands lol

Salt is not needed for most fish. Some fish prefer harder water, and the raised TDS you get when adding salt can get the conditions closer to those preferred. However--'aquarium salt' is not required--other methods that increase hardness are better, IMO. Many fish will not do well in salted water. And, since very people have a reliable way of determining how much salt is in there tank, it can cause problems in the lond run. For example, if you add 1 tsp of salt with each water--but do not take into account that water evaporates leaving salt behind, you will eventually have elevated salinity that can be fatal. Also, it means you need to take additional care in acclimating new fish, since they likely did not have salt in their water at the LFS.

Of course, I also feel obligated to point out that adding "FW Aquarium Salt" does not produce a bracksih environment. It just makes salted water--similar to what you boil pasta in. For brackish conditions, you require the trace elements found in marine salt mixes.

i own 6 mollies and the only time i used salt in their water is when we had a parasite outbreak.other than that i don't use it and my fish are doing great.i have a bubble wand in mine and the fish love swimming up and down in it.my mollies are pretty active and when i feed them,and my fingers are in the water,they will nibble on me,hehehe