Okay, no changing of the filter cartridge! lol You are killing your cycle when you do that. *crazysmil Read the post "High nitrates, new fish owner" by Imcharo (it's in this same subforum) to see why you don't change the filter cartridge. Yes, the manufacturer tells you to do that...why? So they can make money! If you change your filter cartridge, you take out the majority of the good bacteria that keeps your tank in balance and your fish healthy and happy.
Next, is the algae brown? If it is, those are diatoms and they are caused by overfeeding. Remember that your fishes' stomachs are about the size of their eye, so feed accordingly. The water is cloudy because your tank keeps going through mini cycles when you change your filter cartridge and remove all that beneficial bacteria. You're having bacterial blooms as the tank tries to right itself again. The white stuff on the filter and heater is pretty normal (at least it is on my tanks). I'm pretty sure it's just hard water deposits.
Live plants are AWESOME for helping keep your tank clean and balanced. Check out how many watts the light is on your tank and then we can suggest some that would work well with the lighting you have.
Also, if you don't already have a test kit, get one. The API liquid master test kit is WELL worth the money (especially since it lasts for 800 tests!). That way you'll know the exact parameters of your tank at any given moment.