I try my best to answer you...
So, IMO...
First, you put too much fish in your 1 feet tank already, since you just started the number of fish should be less than half of what you have right now. Cause the ammonia or fish shit they produce will be too much and will be toxic to them. And your filter is what type and rated at how many liter/hour???
Second, what kind of lighting did you get??? Only light with spectrum of 6500K-10000K can be used in the planted tank, cause this is the only spectrum that plants use for photosynthesis, 8-12 hours a day. And how many watts is the lighting???
Third, IME co2 can wait, plants can grow without co2, just not as nice. Can start with DIY later, cheaper... But since your curious, here is a link
http://www.my-mac.net/forum/viewtopic.php?...it=co2+diffuserFourth, If you don't have soil then what are you using currently??? I'm curious??? You can get the soil in any LFS selling planted tank related stuff, or you can guide yourself to a LFS near you by referring yourself to the first few post of this thread where there is a directory of all the LFS which sells these stuff. And most planted tank if not all uses ADA amazonia soil...
Fifth, get a dechlorinator, even cheap RM1

will do and just use a pipe to siphon out the debris and usually change only 20-30% of the water each week.
What I mention here is what I have done, what I'm doing

and it differs between different hobbyist. And you can change it to match your own tank...
And my advice to you if you want to improve the survival rate of your fish, get a bag of activated carbon, rinse it and put it in the tank ASAP. You can take it out after 1-2 weeks. It'll suck up all the ammonia and other chemicals and keep the water clean.
How to scape can wait until you get your soil and what fertilizer to use can wait a few more weeks after that... IMO...
I hope I answered all your questions...
Anyone want to add in or offer your opinion on my explanation, please do... I'm learning still
Lastly, welcome to the planted aquarium hobby

For 18-20W, I manage to find only 6500K tube. Is there any tube with higher spectrum than this?
Pls advise.