Welcome to the hobby! Sorry you had a bad first time experience.
FYI, take fish store advice with a very large grain of salt.
Your tank is also severly overstocked. I would dare say that the 6 mollies would have put it at full.
Personally, I would return all the mollies and the pearl (gourami?), this will also signifigantly ease the bioload on your tank and lessen the amount of harmful ammonia being produced.
Next, like everyone else said, get ammonia, nitrite, and nitrate test kits as they are vital to know what's going on in your tank. Also, change 50% of the water daily, as happy said, it will not hurt your fish. I would also recommend you read the sticky at the top of the FW newbie forum page so you know what's going on in your tank right now (and so you'll know what to do if you set up a new tank next time

).
Finally, I haven't ever experienced any FW fish have a problem with table salt dosing up to 2tbsp/10g. The neons will be fine, IMO, and the salt is important to battle ich. I would quit using the medication and use the heat/salt treatment. Here's how you do it:
Raise temp (slowly!

) to 85F and add 1 tablespoon of table salt (NaCl) per 5-10g of water. IMO, it should be done for a complete week even if the fish no longer have symptoms of ich (to be completely sure that the parasite is gone). After that week, take a couple days to lower your temperature back down to between 75-78F. Long term, temperatures over 78F usually cause Neons to slowly waste away so it's important to get them back down once the treatments complete.
Once your tank has finished cycling, you may begin to slowly add fish to your tank (after doing research and picking out fish that match your tank as far as aggression and tank size... remember, research is VERY important). And, avoid impulse buying... it'll usually just get you into trouble

.
HTH and good luck
