Right now the best thing to is step back and let the tank be. Small water changes (a gallon, tops), maybe three times a week are the most you should be doing. Do not change the filter. Do not add any additional fish. Do not worry about plants right now. Do add the decor back to the tank- it will help reduce the stress of your fish.
Basically by cleaning the tank the way you did, you completely wiped out your bacterial colony. Bacteria grows on everything in the tank, but mostly in your filter and your gravel. Fish tanks are not sterile environments, which is very important to keep in mind. It's more stressful for them to be in something 100% clean than for the tank to be a little dirty. The ich that killed your Danio was from stress- not from anything being dirty or infected. Yes, you can help rid the tank of the ich parasite by using heat and vacuuming the gravel, but the most important thing is to target the source of the stress, which in this case is your cycle. So like I said, the best thing to do right now is to help reduce the toxicity of the water with small, frequent water changes and let the tank do its thing.
Plants won't have a whole lot to live on until your tank is cycled- they eat nitrates for nutrients and use light, and at this point in your cycle, you have no nitrates to feed them. The process of plants them and such may stress out your fish more than necessary.
Once everything is settled, try finding some Java fern, Crypto plants, or Anubias. They tend to grow the best under lower light conditions (that most basic tanks offer) and without CO2 injections.
Until you have acquired a larger tank, I don't recommend adding any more Danio. Danio are not only schooling fish, they are incredibly active schooling fish. The confines of a five gallon tank do not give them the appropriate swimming space they need and will cause them even more stress. Your glofish is best left alone until you cycle runs its course and you have a larger space to put him in.
If you keep us updated with the your water's parameters, we can let you know how things are going!