Hi Alie,
Sounds like your Ficus Elastica aka rubber plant aka rubber tree is suffering from overwatering.* This could have started before you purchased it.* The clues for me are the combination of falling leaves and the brown tips.* It's best to let the top 2" of soil dry before watering.* If it's not too rootbound you can stick your finger into the soil up to the first knuckle to see if it's dry.* Over time you will just know how often to water.* Never let a houseplant sit in water in the saucer for more then 15 minutes.* If it continues to drop leaves and looks unsightly you can start again by air layering, cutting the main stalk and rooting it in soil or perliet, using a cutting from the stem aka stem cutting or taking cuttings of the side branches and rooting in either perlite or moist potting soil.* The propagating soil should only dry out about an inch below the surface until roots have formed.
http://aggie-horticulture.tamu.edu/i..._elastica.html
http://www.bellaonline.com/articles/art13123.asp
Here's how to propagate houseplants.
http://extension.missouri.edu/xplor/...ort/g06560.htm
It's best not to fertilize a stressed plant.* If you feel you must fertilize, it would be best to use an organic fertilizer such as fish emulsion with sea weed.* That will gently feed the plant.* Synthetic fertilizers contain residual salts that plants don't need and are like sterioids for your plants.* Best to feed gently.
Sounds like the bugs in your caladiums are fungal gnats.* They certainly are pesky, but tend to be harmless unless they are in large quantities.* They are attracted to soil that is kept too moist. Slices of potato can be helpful in getting rid of them.
http://www.extension.umn.edu/project...ngusgnats.html
You can also make an alcohol spray for the soil only.* DO NOT SPRAY ON YOUR PLANTS.
Mix four parts water with three parts rubbing alcohol into a spray bottle. Spray the mixture around topsoil and infested areas.
Sticky traps also help.* Here's how to:
http://www.ghorganics.com/page9.html#Fungus%20Gnats:
More natural remedies for insect pests.
http://www.ghorganics.com/page9.html
Newt
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.